The process of linguistic standardization of Serbo-Croatian was originally initiated in the mid-19th-century Vienna Literary Agreement by Croatian and Serbian writers and philologists, decades before a Yugoslav state was established. From the very beginning, there were slightly different literary Serbian and Croatian standards, although both were based on the same dialect of Shtokavian, Eastern Herzegovinian. In the 20th century, Serbo-Croatian served as the lingua franca of the country of Yugoslavia, being the sole official language in the Kingdom of Yugoslavia (when it was called "Serbo-Croato-Slovenian"), and afterwards the official language of four out of six republics of the Socialist Federal Republic of Yugoslavia. The breakup of Yugoslavia affected language attitudes, so that social conceptions of the language separated along ethnic and political lines. Since the breakup of Yugoslavia, Bosnian has likewise been established as an official standard in Bosnia and Herzegovina, and there is an ongoing movement to codify a separate Montenegrin standard.
the procEss Of linguiSTiC StandardIZAtiOn oF SERbo-cRoatIAN wAS orIgINAlLY IniTIATed In The mid-19tH-centuRy vIeNnA LiterARy agrEement by croAtian and serbian WrItERs and philoLogisTS, decades bEfore a yugoslAv state WAs establiSHED. FroM The very beginniNg, thEre WerE slIGHtly dIFfeRenT liTerArY SeRbiAN and croatiAN staNdaRdS, alTHOUgH both weRE Based on thE same DialeCt Of ShtokAviAN, easTErN HerzegoviNIAN. In THe 20th cEnturY, sErbo-cRoAtIAn serVed aS The LiNgUa fraNCA oF the countrY oF YugosLavIa, beiNg THe sOlE OfFiciAl LaNguaGe in The kINGdom of yugoSlavia (wHEn It Was caLlEd "serbo-CRoAtO-slovenian"), aNd afteRwardS The oFficial LANguage of four OUT oF six rePuBlics Of tHE soCIAlisT FeDerAl RepublIc Of yUgoSlaVia. thE bREAKUp of yuGoslaVia AfFectEd language atTItudeS, so thAT sociaL coNcePTIOns of the lanGUage sepaRated aloNg etHnic and PolItical linEs. Since The breAkUP oF YugoslaVia, bosniAN haS likeWIsE BEen establisheD As an officiAL stanDaRd in BoSnia And herzegovina, and There is AN ongoiNG MovemeNt to codify a sePArATe MontenEgriN sTanDaRd.