Native English speakers, can you tell the difference between a native English speaker and someone who is very fluent but learned it as a second language? What gives it away?

Yes, mostly through accent (regional accents) and dialects of English. Eventually, they'll blend until someone not specifically trained and exposed to language learners might not.

It's very case-dependent. Some people have "tells" that flag them as perhaps, probably, or definitely not a native speaker, and some don't. Those tells can vary a lot from native language to native language and from person to person, and could be anything from accent to difficulty pronouncing a given sound to unusual phrasings/structures/usage, or any combination of the above. Of course, for non-native speakers for whom there's no noticeable difference, many native English speakers won't realize that it's a second language for them and thus won't know that they didn't pick up on it.

As an anecdote, I work at a restaurant where 99% of the people in the back are immigrants who picked up English and a second language. The vast majority of them don't speak very good English at all, but it's enough to get by. But there's one guy in particular who has lived in the country for like 20+ years at this point, and his English is incredibly solid. Unlike with everyone else, I can have solid and meaningful conversations with him in English and feel understood. But despite that, his accent is still very noticeable. And once you realize that, you can start to notice other inconsistencies, usually with grammar [and then there was one instance where he didn't know what the word "sibling" meant, but I think that's the only vocab issue I've noticed]. That being said, hypothetically, if I found out he was teaching other people from his country English as a second language, I'd absolutely support it and trust that his students would learn well and become fluent just fine. It's better to have a solid grasp on the language, even with minor imperfections, than to not have an accent and obviously have learned English as a second language. A native speaker might be able to patch up any holes in your knowledge, but before you get to that point, you need to have a solid understanding of the concepts, the sentence structure, and grammar, and you don't necessarily need a native speaker to get you to that point.

"Hey yo. Fuhgeddaboudit pal" Some things you learn only by hearing them on the street, and then by sensing the context. Context cannot be taught, because context is NOT language - context is CULTURE. American CULTURE colors American language. Thats why an American in London is easily identified, even though he speaks English. Thats why an American from Brooklyn is easily identified in Key West, even though he speaks English. "Your attention please. Please do not undertake your intentioned activity, my friend." A dead give away.

The only way we can tell is if your accent is foreign or if you mess up in a way that isn’t normal for natives. Natives commonly mess up the counting rules for nouns because sometimes it’s rather illogical for instance, but; not a single native will pretty much ever mess up a phrasal verb in normal conversation. There is one case where it does happen but it’s not a product of them not knowing the verb it’s a product of them changing their phrasing to make more sense. Basically if I change a normal verb to a phrasal verb and my current syntax is incorrect for the phrasal verb I will re-say what I just said to correct it. But this isn’t that common. (Then again this could just be a weird thing that I do and other don’t) Also about accents here’s the common hallmarks of the most common foreign accents I’ve heard - Chinese: has a strange melodic bounce to it that sounds off also used d and s for th - German: rhythm is correct, but z for th and incorrect(slightly) vowels are used. says w as v - French: absence of final consonants in situations where the final consonant is required for understanding, and an almost Slavic tone of voice that almost confuses me as to where there accent is from. Uses z for th - Indian: similar rhythmic bounce without tonal melodic element. Uses d and t for th(mostly d) and uses v for w. - Japanese: sounds like their teeth are glued together. Also uses z for th and final consonants get appended vowels. - Korean: has trouble distinguishing between voiced and voiceless consonants. Has an almost correct cadence uses d for th confuses l for r. - Russian: has a guttural tone of voice and has a way of saying sometimes the wrong vowel but getting close enough to the right one that it’s intelligible. Th is all over the place sometimes they get it right other times it’s like “what is that”. - Spanish: has some issue with th generally if they aren’t from Europe they use d/s otherwise they say it fine all the time. Vowels are generally fine if from Europe with a few exceptions but that depends on the person and the final part of words commonly get a vowel even when they don’t have one in especially thick cases. - Dutch: almost imperceptible unless extremely thick. If they can pronounce th and w right they sound native. For context Dutch and English are almost mutually intelligible in a lot of cases. That’s how close they are. It’s worth noting that the extreme elements of each accent even native ones will make people harder to understand (thick Scot’s Carrey Irish, Newcastle English, Newfoundland Canadian and Appalachian American are some of the best examples of that). So just know that while these can be hallmarks language is pretty much a person specific thing so if you want to guess their native language you have know something about the language first which is how people get called out for used have idioms and being called a native romance language speaker. Sometimes it’s correct other times it isn’t. Context matters.

Ironically the way to tell the difference between someone who is native and someone who is very fluent is that they are *too* fluent. They speak in a strictly proper way and don't take any liberties with grammar that arise from a lifetime of hearing a broad mix of dialects/vernaculars from subcultures within the language. This is how we can tell when we're dealing with someone on the phone who is local vs. someone at an offshore call center. It's typically India where the call centers are and Indians by and large have a very strong command of English, they enunciate words fully, avoid casual non-traditional contractions. They speak it very well, *too* well to pass as a native speaker. Native English speakers generally know the rules they're breaking, but have learned when it's OK to break them in some contexts when not in a formal setting. Learners from other languages rely more heavily lean on strict grammar guidelines until they consume enough native culture to figure out which rules can be bent.

The only people who could I've ever been on the fence about are people from Northern Europe People from the Netherlands, Denmark etc. sometimes have such good English they could pass as native speakers.

Being English we grow up with very precise accent hearing. So I will always know the difference between someone who grew up in South West London and South East London, as well as the obvious differences between neighbouring cities like Manchester and Liverpool, as well, of course, of all the class differentiators between people from the same area. So when English people hear a non-native English person they will immediately know that English is their second language, where their first English teacher came from, and what part of England they are living and working in now, and usually what their native tongue is (although probably not between, say, different Slavic countries).

I’m British so yes, they tend to speak it better than us.

It’s very very rare to ever hear a non native speaker sound like a native. Dutch people can come close if they’ve lived in the uk a long time.

The structure of the sentence will probably differ compared to native speakers.

I identify Europeans by grammar. Theirs is better than ours.

Yes always, unless they live here and have mastered the accent. But even then, there are giveaways in the pronunciation of certain words. Hard to give an example without hearing.

Accent, linking, prepositions and formality. One of these usually tips me off I'm gonna wake-up tomorrow at 8 and grab breakfast vs I'm planning to wake up at 8am in order to have breakfast

One of my friend’s stepmoms is from the Philippines but moved here at the age of 6 and learned English basically completely by immersion. Her English is perfect, but she sounds ever so slightly different than everyone around here. Only enough to notice if you’re really paying attention though. So yes, I can usually tell but some cases are harder than others.

For me, it's spots of overly correct grammer and as someone else posted some sounds like 'sq'. For me, 'kn' and especially the word 'known' seems to carry inflections from their native language.

It's usually a missed or incorrectly used collocation

Accent, idioms and slang (lack of the use of either), using more formal speech. Those are top of mind things that give away a non-native speaker. But...none of this is actually important. It doesn't matter to a native speaker if you have a non-native accent. It doesn't matter if you don't know all of the local slang. As long as you can get your point across, that is what matters.

Apart from accents, which have already been discussed a lot, the easy answer is "use of phrasal verbs". Specifically, there's a few super fluent C2 speakers who could've tricked me into thinking they were native... and the only little thing I ever noticed in either of them was that they always used, "In the end..." and never "after all" or "ended up". "In the end, we did go to the concert." "In the end, it rained anyway." "We ended up going to the concert after all." "We brought umbrellas, but it didn't rain after all." (as for the OP description below the title question -- if you can't tell the difference, then it clearly doesn't matter. You're talking about such fine details that even a very fluent C2 speaker is missing, and you want to be even better than them to the point of being native, as a second language speaker? That doesn't make much sense. Besides, people who learned English proficiently as a second language are often *better* English teachers than us native speakers, because they *had to* learn all the rules and go through all the difficult parts -- we didn't :) )

If you learned English after the age of ten or so, it doesn't matter how fluent you get, your accent will clock you for the rest of your life. This isn't a bad thing necessarily. It doesn't mean people won't understand you or will treat you differently. It's just a piece of information that native speakers will instantly realize about you (much in the same way that we can spot native speakers with different accents). That said, in terms of absolute linguistic ability to understand and be understood there is no age limitation. Adults can and do gain full fluency in English all the time. Some English teachers who teach native-speakers in schools are themselves ESL. There's nothing wrong with learning English from a non-native speaker. Ultimately though, you are going to end up sounding like the people you speak with the most.

The way they pronounce things. Even the most fluent speaker will have at least a little bit of an accent

I'm not sure that you should be too worried. If I hear English spoken with a foreign language it means that you speak more than one language, so are at least one up on me, and deserve my admiration.

For me I only really have my husband to study this phenomenon with as his 2nd language was English and mostly self taught through gaming. What gives him away was his accent, putting stressors on the wrong syllables of certain words, and general mispronounciations/stressing of words that tend to be root words of other (think like pronouncing Japan as if you were about to say the word Japanese). But they're mostly tiny lil things here and there that I don't think anyone but myself pick up on because he mostly only talks to me, and if he does these mishaps in front others they have yet to mention it so it either doesn't bother them enough to correct him or they don't notice it at all.

People who are born in English speaking countries and raised in English speaking environments and speak nothing but English their whole life can inherit accents and develop slight minority language inflections from family and/or community. I went to school with a girl whose father was Finnish and mother was Chinese from Hong Kong. She was born here but said a few sounds in ways that sounded foreign but not any kind of foreign that was identifiable. She is a native English speaker. The idea that there is an homogenous native English speaker, and a singular native English pronunciation and syntax is just silly. Many native English speakers are born into and raised in bilingual families and communities. This can slightly alter the sound of their English but it certainly doesn't stop them being a native English speaker. Additionally, many children of migrants are born into a language minority community and again it would not be uncommon for some audible traces from their developmental language experience to persist in their native majority language. This is common with some native English speakers who grow up in African, Indian, Chinese, Japanese, Greek, Arab families and communities. So trying to "pass" as a native speaker is not something that can be narrowed down to a short list of boxes to tick as there is a kaleidoscopic spectrum of native English speakers. Native English speakers from Edinburgh, Dublin, Johannesburg, Cardiff, Boston, Savannah, Sydney and Stanley, just to name a few, will be astonishingly different native speakers. This is not unique to English. I remember visiting Berlin for the first time and meeting a woman in my circle of friends who was German born from a Chinese family. I couldn't notice anything different about her German and when I asked my German friends if she had an accent or anything, they all said she spoke better German than all of them and they wished they could sound as smart as her LoL. She also spoke amazing fluent English with a very posh British accent and only one or two typical German accent sounds here and there, occasional d's as t's and the tr consonant combination gave her away now and then. The definition of a native speaker is someone who acquired the language naturally through their early childhood development and beyond, but that journey differs for everyone.

Sometimes I can't tell. Usually what makes me wonder is sentence structure. English learners may fall back on subject-verb or adjective-noun order from their native language. Or the sentence structure is verrrry proper. Sometimes vowel pronunciation will be the thing that catches my attention. Or a formality that is common in their native speech, but uncommon in English casual conversation.

Depends. Having an accent usually gives it away.

The use of “how” is a bit of a giveaway when most native speakers would use “what.” Like “how do you call this?”

Preposition use, trouble with gerunds, issues with irregular past tense of verbs

Most very proficient 2nd language speakers 1. do not use contractions and 2. speak more grammatical English than we do. Many people here worry excessively about their accent. Most times, unless you are an actor or news reporter with speaking roles that require you to sound like a native, or communicating primarily with old people, do not need to worry about this. One time I had a hard time understanding a fellow native speaker, because I had not "tuned" my brain for his accent. It took a second to realize he was speaking with a new york accent, but then it was fine.This was a person in my own country. Like I tell my kid, we all have an accent.

Often it's simply the rhythm of spoken speech. I run into this particularly with SE Asians whose written English is superb but the spoken is nearly unintelligible because of rhythm.

Absent an accent, enunciation is often an indicator. Non- native speakers often have crisper enunciation. Native speakers sort of elide over many consonants.

Brits can tell if you come from a different part of their city, or a different town, let alone a different country. There's no way to hide your accent unless you moved here before your teens. I've lived in London 30 years & everybody can still immediately guess where I'm from.

There are many regional variations of English and it's hard for a learner to consistently use one variety. British actors portraying Americans will often betray the difference by mixing varieties. Someone might, for example, be playing a New York banker and, even if he has the East Coast accent down perfectly he may throw in a phrase that is more typically Southern. Regional differences can be subtle. Growing up in the Midwest I could distinguish three accent variations from north to south across Iowa. I don't think I could do that today. After all these years living on the West Coast I would find it difficult to pick up the difference between a central Iowan accent and a northern Minnesota one. I speak a little Spanish but I can only recognize a few of the more distinctive regional accents. All the Caribbean accents sound the same to me but a native might be able to pick up the difference between the accents of the various islands after hearing just a few words. You might be able to speak English so well that no one can guess your native language but it's much harder to hide the fact you have not learned the language in one particular place.

There are small mistakes that add up. You start by going "wait, huh? That sounded odd" and then end up going "ohhhhhhh, she's not a native speaker. Wow, she's really fluent". It's different with every person, though. I also once met a customer at work who was very clearly Chinese, but was speaking the most perfect, meticulous, beautifully enunciated King's English you've ever heard... in a small rural town in the southern United States, where we speak in a low-prestige, but quirky and beloved, local dialect. 😅 Then something flustered him and he started speaking very brokenly, with a notable foreign accent. TwT Poor guy. I wanted to reassure him but didn't know what to say.

One of the biggest give aways is slightly misuse of idioms but obviously that's very regional a lot of the time and linked to age.

It’s usually told by slight variance in vowel quality or consonant articulation. It’s also sometimes given away by certain grammatical forms, especially use of articles and prepositional verbs. These can be really subtle things for L2 speakers but are prominent for L1s.

Yes. Even if you are speaking English fluently from a vocabulary and grammatical perspective, it's very difficult to completely get rid of an accent and sound like a native speaker. I can only think of two people I know who have come to the UK as an adult who now have a British accent. Many will have virtually perfect grammar (probably even better than that of a lot of native speakers) but a foreign accent will still be detectable/strong even after more than 10 years living and working here.

a lot of people i’m around know english as a second language so it’s not even something i bother to differentiate in my head. also many native speakers here have non-native speech patterns because they’re influenced by their ESL parents

Most English natives can instantly tell if somebody learned English as a second language, even if their pronunciation and accent is almost flawless. No matter what, the most subtle differences in vowel sounds, cadence, anything really, will be perceptible and stand out. Which is absolutely fine. It is so unbelievably rare for a speaker of any second language to be perfect to native ears. I have heard it only once in my life, a Danish person with an American accent when speaking English that was actually flawlessly native (not putting on an accent like acting, but his natural speaking). It is isn't one thing, but many subtle differences in sounds that native ears pick up on. 

You can normally tell by ‘incorrect’ use of articles, especially if you are discussing a new issue or topic. The rules for using articles are highly complex and depend on the noun. If a non-native speaker is using unfamiliar nouns which have a particular meaning in an unfamiliar context, they are prone to making errors in a way native speakers wouldn’t. There is a similar problem with prepositions. Non-natives might use ‘the wrong’ preposition, because they are unfamiliar with the way that different prepositions can be used in different circumstances, or they experience interference from their first language, where a specific preposition is used. Native speakers will instinctively think ‘something is wrong’ in these situations because they are expecting a certain article / preposition. They might not be able to say what is wrong, or express a rule that has been broken, just that something unexpected happened with the language. Sadly, as a learner yourself, you won’t have this intuition, so it’s very difficult for you to tell.

I would say 95% of the time I can. I can often tell when others around me can't. I think because I study languages. Even if there is no accent, the thing that gives it away for me is word choice. I have a few international friends who have spoken English their whole lives (as a second language) and they tend to speak a more formal English. And sometimes with a mix of English-speaking accents.

For me, it’s usually the random word or phrase that’s perfectly correct in grammar & meaning but no native speaker uses it in that context. Something like how some of us only use specific words & phrases to satisfy the minimum word count in writing assignments or when writing a book to immerse readers. But the moment someone uses them in verbal conversations, we silently go “dafuq r u doin?”

Yes, I can always tell, assuming they learned English after about age 10. Pronunciation is usually the first giveaway. An inability to use "higher English" or bygone forms is another.

Almost always yes, though in some cases the "tells" are very slight and difficult to even really identify.

I knew a German guy who'd been in America for 20 years when I met him. Very good accent overall but he never completely mastered the R. I gambled on my hunch and asked him where he was from and that's how I found out. I knew a French guy the grew up mainly in France but spent some summers in US. He also basically sounded native but struggled with pronouncing personal names the way they are in English. There is ALWAYS a give away if you talk to someone long enough.

The biggest sign to me is Grammer. My grandparents first language was Spanish and they still phrase some thing like they would in Spanish. I also work with some Burmese people and although their English is great, I get asked to call maintenance "for to change battery" pretty frequently.

I am a US English speaker. For me, it is the vowels and the letter r.

I would say I can tell 99% of the time. The tells vary and can often be very subtle - Accent usually or pronunciation of specific letters/sounds - Word order, e.g adjective order - For those whose first language is a slavic language, I often notice things like: missing/incorrect articles, unnatural use of it vs this/that and vice versa, incorrect/absent prepositions - Unnatural word choice

I have lived abroad, so I’ve befriended many non-native speakers who spoke a very high level of English and have met some people here in the US that are non-native speakers, but are clearly very fluent. It definitely can’t be difficult because it depends on the person and it’s not like I go around looking for errors in somebody’s speech. Accent, of course is a tell adult learners have a difficult time 100% dropping their native accent. The person gonna be completely understood without any issues, but may still have a hint of an accent. Another one would be phrases or wording of things. Misuse of articles or putting articles in a sentence in a place that I necessarily wouldn’t choose. Because English is so weird with plurals and countable and uncountable nouns sometimes that confuses non-native speakers and if I’m really being particular, I could probably pick out somebody that way.

Usually it's the accent.

I'm an English teacher from Germany. I can often spot Germans in comment sections because they use sentence structures that are not quite idiomatic. A different way to assess if you have a German speaking English that my professors at university told us about was the "Auslautverhärtung" - the de-voicing of the last part of a syllable. In German this happens in every syllable, but in English it doesn't. This is almost impossible to get rid of completely, so you can spot Germans by checking if they say "dog" with an actual g or if there is a slight hint of a k. I think that might overlap with some native accents as well though.

Usually a touch of an accent.

Even the best non-native speakers have a tiny little accent, or their speech can sound almost artificial or stilted to hide said accent. Also certain sounds are very difficult for non-native speakers, R's, some vowels (especially short A), the schwa sound (or lack thereof) can also be a dead giveaway. Also the rhythm of the language can be a little off. If you really think about it, spoken English is quite different than written. Words become compressed, or contracted (kinda, woulda, coulda, shoulda being good examples). But as others have said, I'm sure there are non-native speakers who no one can tell, but, we wouldn't realize that they weren't non-native!!!!!

I can *usually* tell. It’s usually very subtle, like an accent or using a phrase or word just slightly “off.” I will say that I’ve been “fooled” by a lot of non-native speakers! I work in an international office, and and few times I’ve thought the person was American. Nope, just very good English.

I am a native speaker of English working as an English Tutor, have lived in 3 English speaking countries, including the UK, and most British people are able to tell that I am not British, although to most people I have a British accent.

Generally yes, but it's not something to worry about either. Why would you want to hide that you're not a native soeaker? Be proud of your own background and being fluent in more than one language.

Yes, it's very rare that a non-native speaker doesn't have at least some trace of a foreign accent.

It’s mainly accent, but I have to say that in my experience a lot of English learners are *strongly* resistant to inverting questions, and not inverting questions is one of the single biggest tells.