Are Croatian, Serbian and Bosnian the Same Language? A Linguist's Answer
Nine days ago I put a video on YouTube answering the question I get asked more than any other. Are Croatian, Serbian and Bosnian the same language. I gave my answer in the first minute — Croatian is a language, and it is not the same language as Serbian — and then I spent the next fifteen minutes showing my evidence, naming every scholar I was leaning on, and telling you plainly where that evidence runs out.
More than seven thousand people watched it in the first week. Four hundred and seventy-four comments piled up underneath it, which is a great many comments for a channel my size, and I read almost all of them.
Some were generous. A few were genuinely learned — there is a retired-sounding gentleman in the replies quoting Kašić and Marulić back at me with more citations than I used in the video itself, and I mean that as a compliment. A good number were people arguing with each other and had visibly forgotten I was in the room. And a great many were furious. I was called a liar, a chauvinist, and an embarrassment to my own profession. One commenter had thought about his diagnosis and settled on “non-linguistic issues.”
None of that surprised me. I have been doing this too long to be surprised by it. What surprised me was which sentence they chose.
Somewhere past the seven-minute mark I say that I do not understand Serbian perfectly. I follow a conversation, I watch a film and I am not lost, but there are ordinary words — kitchen words, hospital words, hardware-shop words — where I hit a wall and stop. Then I said, as carefully as I know how to say anything, that nobody has properly measured this, so take it for exactly what it is: what one linguist notices at her own kitchen table.
It was the most hedged sentence in the entire video. By the time it reached the comments it had becomeshe says she can’t understand Serbian films, and underneath that someone told me to get help.
I am telling you this because I suspect a good number of you have already sat in that comment section, just in person, at a table rather than a screen. Somebody — an in-law, a colleague who once did a semester in Belgrade, a well-meaning stranger at a diaspora picnic — told you, with total confidence, that it is really all one language. And you, halfway through learning your grandmother’s Croatian, or trying to pass it to a child who resists it, did not know what to hand back.
I want to give you something to hand back. Not a slogan. The actual argument, the sourced version, the one I did not have time to give in eighteen minutes of video.
But first, the comments that were worth keeping.
What was worth keeping
A man named in the comments only by his handle wrote about starting school at a Frenchlycéein the late 1970s and then transferring, as a small boy, into third grade at a school in central Zagreb. On the first day, in a lesson on how children should cross the street, he used the word his family used at home for a crossing —križanje— and his teacher corrected him sharply in front of the class. He is not a young man now. He still remembers exactly how it felt.
I want to be precise about why that story matters to me, because it would be easy to read it as a complaint about a strict teacher, and it is not that at all. It is a demonstration, delivered by a stranger on the internet, of the entire argument of this letter. A standard language is not something anyone absorbs by simply growing up inside a speech community. It ismade— selected, written down, taught, corrected — and it is felt in a child’s body, as a small public humiliation over one word, decades before that child could ever have followed an argument about diasystems and criteria. Every heritage speaker I teach carries a version of that boy’s morning. Usually it happened to their parents, over some other word, at some other kitchen table, and it is why the parent stopped correcting the child’s Croatian at all.
Another commenter, writing from Međimurje, described the dialect at home shading gradually into the Slovene spoken just across the border — a comment written entirely in the register of somebody who has never needed a linguist to tell him a continuum exists, because he has been living inside one. And a Macedonian linguist, writing with real generosity given how badly the video had gone in the replies above his, compared my situation to his own relationship with Bulgarian: two national standards that overlap heavily, understood asymmetrically, freighted with a much older and uglier political history than either of us invented.
Those three comments, from three strangers, made the video worth the eighteen minutes it took people to sit through and the several hundred it took people to argue about. They are also, not coincidentally, the three comments that came from people who were not trying to win anything.
The two objections that deserve a real answer
Underneath the noise, two real arguments kept recurring, made by people who plainly knew what they were talking about, and I owe both of them a proper answer rather than a shrug.
The first: Croatian, Serbian and Bosnian share a common linguistic basis, built from the same neo-štokavian material, so on what grounds do we call them different languages rather than one language with three names.
The second, more sophisticated version of the same objection: English has British and American forms, Spanish has Iberian and Latin American forms, and nobody calls those separate languages. Linguists have a word for exactly this situation — pluricentric — so why not simply apply it here and stop arguing.
Both deserve a section, because both need sources, not just conviction.
Same basis, different building
The honest version of the “same basis” objection is arithmetic, and it comes from a colleague of mine at the University of Zagreb,Marko Alerić, in Pravo na jezik,published in 2024.Croatian has three narječja— štokavian, kajkavian, čakavian, named for how each says the word “what.”Serbian, on Alerić’s count, has two — štokavian and torlakian (Alerić 71–72). I should say plainly that this count of Serbiannarječjais Alerić’s own, and that not every linguist divides Serbian dialectal space the same way. I am telling you whose claim it is rather than presenting it as arithmetic nobody disputes.
Fivenarječjabetween the two languages. One shared.
And then the part that actually carries the argument: the Serbian standard was built on štokavian alone. The Croatian standard was built on all three — and still is, in its ongoing revision, today (Alerić 71–72). That is not a claim invented in 2024 to win an internet argument. Bartol Kašić designed the very first Croatian grammar, in 1604, as a deliberate combination of čakavian and štokavian material, which is what the so-called Zlatna formula —ča, kaj, što— actually names, and which Alerić notes is now protected as a cultural good of the Republic of Croatia (Alerić 72).
So: shared starting material, yes, for one of three dialect bases, and not for what was subsequently built on top of it. Alerić has a school-essay corpus of about 450 essays by Croatian children that makes this concrete rather than abstract — a child who writespark kojeginstead ofpark kojiis doing that because kajkavian does not distinguish animate from inanimate objects in the accusative case, and a child who drops the final-iin an infinitive is doing that under štokavian and čakavian influence, and does itlessif she happens to be a kajkavian speaker, because kajkavian preserved a distinction the standard lost (Alerić 352–58). You can read all three dialect bases directly off a fourteen-year-old’s mistakes. That is not the same foundation as the standard next door, and it is not close to the same foundation.
But I want to be honest about something the more careful commenters raised, because it is the better argument and it deserves to be treated as one: none of this settles anything by itself, becausemutual intelligibility has never been the criterion for what counts as a separate language, anywhere on earth.Danish, Norwegian and Swedish are mutually intelligible to a high degree, and written Norwegian Bokmål grew directly out of written Danish because Norway was governed from Copenhagen for four centuries — and nobody, not linguists, not Danes, not Norwegians themselves, calls Norwegian “not a real language.” In the other direction, what gets called Chinese covers varieties — Mandarin and Cantonese among them — that are not mutually intelligible in speech at all, a distance comparable to that between separate Romance languages, and they are conventionally treated as one. Comprehension is neither necessary nor sufficient. It never has been.
The scholar who put this most usefully is the Zagreb linguist Dubravko Škiljan, writing in 1980 — inside Yugoslavia, from a position of real discomfort with every nationalist reading of language on every side of that argument. Attempts to define a language’s identity purely from its internal levels — its phonology, its morphology — have on the whole not succeeded, Škiljan wrote, and so a language has to be accepted, for the time being, as a phenomenon that grows in the consciousness of its speakers out of a tangle of linguistic and non-linguistic causes together, shaped heavily by deliberate interventions like standardisation (qtd. in Alerić 57–58). His definition of a language, elsewhere in the same book, is a system whose speakers feel a common belonging to one means of communication (qtd. in Alerić 57–58).
The German sociolinguist Heinz Kloss gave the field the clearest tool for separating the two kinds of question people keep running together, and he did it in 1952, decades before this had anything to do with the former Yugoslavia. Varieties become “languages” for two structurally different reasons.An Abstandsprache is a language by distance — structurally isolated enough from its neighbours that there is nothing else it could be called, the way Basque sits inside Romance Europe. An Ausbausprache is a language by development — elaborated deliberately, given a grammar, a dictionary, an orthography, a literature, a body of law and administration conducted in it (Kloss 29). Norwegian is anAusbaulanguage. So is Slovak. So is Macedonian. So, by exactly the same criteria, is Croatian, which has had a grammar since 1604 and a Constitutional status as an official language since Croatian independence, an EU-official status since 2013 with its own interpreters in Brussels, and — as of a vote in the Sabor on 26 January 2024, ninety-five in favour to seventeen against —its own statute, the first time Croatian’s public and official use has been regulated by law. Institutionally and legally, in other words, this particular question closed some time ago; the argument that continues is a live and serious one among linguists about how best todescribe the relationshipbetween the standards, not about whether Croatian exists. Even scholars who disagree with me on the harder theoretical question do not say that.
The Zagreb linguist Radoslav Katičić, who held the chair of Slavic studies in Vienna after two decades at the Zagreb faculty, offered three criteria for linguistic identity in his essay “Identitet jezika”: the genetic (where a variety historically came from), the typological (how it is structurally built), and the cultural or value criterion (the body of writing and tradition a community recognises as its own). Idioms that coincide on all three are one language; idioms differing on even one are not (Katičić). Some people treat that third criterion as softer evidence than morphology. I think that is exactly backwards, and Škiljan told us why more than forty years ago — the structural criteria were tried, on their own, and did not do the job. The cultural criterion is the one doing the actual work. It is the criterion that makes Norwegian, Norwegian.
The Declaration says the opposite of what people think it says
No document gets invoked in these arguments more, and read less, than the 1967 Declaration on the Name and Status of the Croatian Literary Language,published in the Zagreb weeklyTelegramon 17 March of that year and drafted by a commission that included both Brozović and Katičić — the same two scholars whose theoretical frameworks I have just walked you through. The signatories were condemned for it; careers were damaged; Miroslav Krleža resigned from the Central Committee of the Croatian Communist Party that April in written protest.
Here is what it actually says, and I want you to read the sentence in full, because the full version is the one people never quote:
Takva se praksa ni u kojem slučaju ne može opravdati inače neosporenom znanstvenom činjenicom da hrvatski i srpski književni jezik imaju zajedničku lingvističku osnovu. (qtd. in Alerić)
Such a practice cannot in any case be justified by the otherwise indisputable scientific fact that the Croatian and Serbian literary languages have a common linguistic basis.
They conceded the common basis. In writing, in the document that people invoke as the great assertion of Croatian linguistic separateness, the drafters stated outright that the common basis is not in dispute. Their argument was never about distance. It was aboutthe inalienable right of every people to call its language by its own name— regardless, they went on, “of whether we are dealing with a philological phenomenon which, in the form of a separate variant or even in its entirety, also belongs to another people” (qtd. in Alerić). Even in its entirety. They granted the strongest possible version of the case against them and argued that it would still not settle the question of the name. And the Declaration’s very first demand was constitutional equality for four literary languages — Slovene, Croatian, Serbian, Macedonian, named together. The scholars I am quoting spent their argument claiming a name for their own language while granting the identical right to everyone standing beside them.
The concrete grievance behind the Declaration was that the constitutional formula of the day,srpskohrvatski odnosno hrvatskosrpski, was vague enough in practice that one of the two names became the default state language — through the federal army, the railways, the post office, the newsreels — while, in the drafters’ own words, the Croatian literary language was pushed aside and “brought into the unequal position of a local dialect” (qtd. in Alerić).
Notice what the drafters did not do. They did not argue that Croatian was structurally far enough from Serbian to count as separate on distance alone — we have already seen that they conceded exactly the opposite. They argued for a name, on the single ground that a people has an inalienable right to its own name for its own language, and they extended that same right, in the same document, to everyone standing beside them. That is the tradition I speak from, and it is why I will not adjudicate anybody else’s language, and it is also why nobody is entitled to adjudicate mine.
Why “pluricentric” does not quite fit
The second serious objection is the better one, and it is the one a linguist would actually put to me rather than a comment section. English, Spanish, Portuguese and French all have multiple national standards, and linguists call languages in that situation pluricentric without anybody concluding that British and American English are separate languages. Why not simply say the same thing here and stop arguing.
Because of how those cases came into being. In every canonical example of pluricentricity, one people crossed an ocean or a border, settled, and over generations built a second standard version of a language it had carried with it: one people, then two communities, then eventually two standards. That is not the shape of what happened in the former Yugoslavia. Here, two peoples with an already clear national consciousness, separate literary histories, and separate standard languagesalready formed and already in usewere subsequently asked to share one common standard, rather than the reverse. Alerić calls this a genuinely unique case among the world’s pluricentric languages (Alerić 81), and adds a test worth keeping: if pluricentricity were established merely by the criterion of a shared ancestor language, the category would very quickly swallow most of the languages on earth, which is a polite way of saying that a category explaining everything explains nothing (Alerić 82).
This is not new, and nobody invented it
I want to deal with one claim directly, because it is the one that circulates most carelessly, and because settling it does not require theory at all — only dates, which you can check yourself.
There is a story, repeated constantly and by people who would never accept the equivalent claim about their own language, that Croatian was invented in the 1990s for political convenience. It was not.
There was a printed Croatian missal in 1483, in Glagolitic script, appearing within decades of Gutenberg’s press itself. Bernardin of Split’s lectionary followed, printed in Venice in 1495. Marko Marulić finishedJuditaon 22 April 1501, printed in Venice in 1521 — the first work of original Croatian literature, which is why Marulić is called the father of Croatian literature. And in 1604, in Rome, Bartol Kašić publishedInstitutionum linguae Illyricae libri duo, the first grammar of Croatian — one of the earliest grammars of any Slavic vernacular, at a time when most of Europe’s languages did not have one at all. HisRitual rimskiof 1640 went further than a grammar ever could: it was the book read aloud at every baptism, every wedding and every funeral across Croatian lands for centuries, which is how a written norm gets into the mouths of people who never opened a grammar in their lives.
You may argue about a great many things in this dispute. You cannot argue about that. A language with a grammar from 1604, a literature in print from 1521, and a printed book from 1483 was not invented sixty years ago by anyone, and it has of course changed since 1604, the way every living language changes — that is not a concession, it is just what it means to be alive rather than fossilised.
What actually changed is not the language — it is the machinery around it
For most of the twentieth century, Croatian and Serbian were held close by machinery that had nothing to do with grammar: one federal army every young man passed through, one broadcasting system, one film industry, one news agency, one set of official forms. I said in the video, and I meant it as an observation rather than a study, that I understand more Serbian than my own children do, and the reason is not that Croatian and Serbian are more alike in my generation. It is that I spent twenty years being exposed to Serbian by a state built to expose me to it, and my children did not.
That machinery has been gone for thirty-five years. Croatia has had its own institutions, its own broadcasters, its own schools setting their own norms, for the whole of that time, and in that time the two standards have not stood still. They have each continued doing what every living standard does — drifting, borrowing, regularising, revising its own dictionaries and its own norms — but now in two separate rooms instead of one shared one. Nobody sat down and manufactured new words to make a political point. That is simply what happens to two related standards once the single administrative apparatus holding them artificially close for seventy years is removed. Two related languages, left to develop independently, develop independently. That is not invention. It is not even unusual. It is just what languages do once nothing is forcing them to do otherwise.
What to actually say at the table
If you take one thing from this letter rather than the whole argument, take this. You do not need to win the theoretical debate at a family lunch, and you are not required to have Alerić’s page numbers memorised. What you need is the shape of the answer: the common basis is real and nobody serious denies it, but the standards built on top of that basis were not built the same way, on the same dialectal ground, or by the same historical process; the language itself is not new, and has been continuously written, printed and grammatically described for more than five hundred years; what has genuinely changed is only that nothing is left forcing two related standards to converge, so of course they are drifting further apart, and that is ordinary language behaviour rather than anybody inventing anything; and every people, including yours, has the same plain right to call its own language by its own name. Say that much, calmly, and you will have said more than most of the four hundred and seventy-four people arguing under my video managed to say to each other, or to me.
Works Cited
Alerić, Marko.Pravo na jezik. Školska knjiga, 2024.
Declaration on the Name and Status of the Croatian Literary Language.Telegram, no. 359, 17 Mar. 1967. Institut za hrvatski jezik i jezikoslovlje.
Katičić, Radoslav. “Identitet jezika.”Novi jezikoslovni ogledi, 2nd ed., Školska knjiga, 1992.
Kloss, Heinz.Abstandsprachen und Ausbausprachen. 1952. Cited from 1967 restatement, p. 29.
Škiljan, Dubravko.Jezična politika. 1980. Quoted in Alerić, pp. 57–58.
Zakon o hrvatskome jeziku.Hrvatski sabor, 26 Jan. 2024.
Tihana Klepač is an Associate Professor at the University of Zagreb’s Department of Englishand the founder of TalkTime Croatian.She teaches theCroatian Quadrant™, a structured, culturally immersive course designed to help learners stop translating and start thinking in Croatian. Find out more at talktimecro.com
This letter was originally published in Saturday Letter from Zagreb, my newsletter for Croatian heritage speakers and diaspora learners.
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