Ethnologue: Languages of the World (stylized as Ethnolo?ue) is an annual reference publication in print and online that provides statistics and other information on the living languages of the world. It was first issued in 1951, and is now published annually by SIL International, a U.S.-based, worldwide, Christian non-profit organization. SIL's main purpose is to study, develop and document languages for religious purposes and to promote literacy.
Ethnologue includes the number of speakers, locations, dialects, linguistic affiliations, autonyms, availability of the Bible in each language and dialect described, a cursory description of revitalization efforts where reported, and an estimate of language viability using the Expanded Graded Intergenerational Disruption Scale (EGIDS).
Ethnologue has been published by SIL International (formerly known as the Summer Institute of Linguistics), a Christian linguistic service organization with an international office in Dallas, Texas. The organization studies numerous minority languages to facilitate language development, and to work with speakers of such language communities in translating portions of the Bible into their languages.
The determination of what characteristics define a single language depends upon sociolinguistic evaluation by various scholars; as the preface to Ethnologue states, "Not all scholars share the same set of criteria for what constitutes a 'language' and what features define a 'dialect'." Ethnologue follows general linguistic criteria, which are based primarily on mutual intelligibility. Shared language intelligibility features are complex, and usually include etymological and grammatical evidence that is agreed upon by experts.
In addition to choosing a primary name for a language, Ethnologue provides listings of other name(s) for the language and any dialects that are used by its speakers, government, foreigners and neighbors. Also included are any names that have been commonly referenced historically, regardless of whether a name is considered official, politically correct or offensive; this allows more complete historic research to be done. These lists of names are not necessarily complete.
In 1984, Ethnologue released a three-letter coding system, called an 'SIL code', to identify each language that it described. This set of codes significantly exceeded the scope of other standards, e.g. ISO 639-1 and ISO 639-2. The 14th edition, published in 2000, included 7,148 language codes.
In 2002, Ethnologue was asked to work with the International Organization for Standardization (ISO) to integrate its codes into a draft international standard. The 15th edition of Ethnologue was the first edition to use this standard, called ISO 639-3. This standard is now administered separately from Ethnologue (though still by SIL according to rules established by ISO, and since then Ethnologue relies on the standard to determine what is listed as a language). In only one case, Ethnologue and the ISO standards treat languages slightly differently. ISO 639-3 considers Akan to be a macrolanguage consisting of two distinct languages, Twi and Fante, whereas Ethnologue considers Twi and Fante to be dialects of a single language (Akan), since they are mutually intelligible. This anomaly resulted because the ISO 639-2 standard has separate codes for Twi and Fante, which have separate literary traditions, and all 639-2 codes for individual languages are automatically part of 639-3, even though 639-3 would not normally assign them separate codes.
In 2014, with the 17th edition, Ethnologue introduced a numerical code for language status using a framework called EGIDS (Expanded Graded Intergenerational Disruption Scale), an elaboration of Fishman's GIDS (Graded Intergenerational Disruption Scale). It ranks a language from 0 for an international language to 10 for an extinct language, i.e. a language with which no-one retains a sense of ethnic identity.
As of 2017, Ethnologue's 20th edition described 237 language families including 86 language isolates and six typological categories, namely sign languages, creoles, pidgins, mixed languages, constructed languages, and as yet unclassified languages.
In 2021, the 24th edition had 7,139 modern languages. 
In 1986, William Bright, then editor of the journal Language, wrote of Ethnologue that it "is indispensable for any reference shelf on the languages of the world". In 2008 in the same journal, Lyle Campbell and Verónica Grondona said: "Ethnologue...has become the standard reference, and its usefulness is hard to overestimate."
In 2015, Harald Hammarström, an editor of Glottolog, criticized the publication for frequently lacking citations and failing to articulate clear principles of language classification and identification. However, he concluded that, on balance, "Ethnologue is an impressively comprehensive catalogue of world languages, and it is far superior to anything else produced prior to 2009."
Starting with the 17th edition, Ethnologue has been published every year.
|1||1951||Richard S. Pittman||10 mimeographed pages; 40 languages|
|4||1953||Pittman||first to include maps|
|5||1958||Pittman||first edition in book format|
|10||1984||Grimes||SIL codes first included|
|15||2005||Raymond G. Gordon Jr.||6,912 languages; draft ISO standard; first edition to provide color maps|
|16||2009||M. Paul Lewis||6,909 languages|
|17||2013, updated 2014||M. Paul Lewis, Gary F. Simons and Charles D. Fennig||7,106 living languages|
|18||2015||Lewis, Simons & Fennig||7,102 living languages; 7,472 total|
|19||2016||Lewis, Simons & Fennig||7,097 living languages|
|20||2017||Simons & Fennig||7,099 living languages|
|21||2018||Simons & Fennig||7,097 living languages|
|22||2019||Eberhard, David M., Simons & Fennig||7,111 living languages|
|23||2020||Eberhard, Simons & Fennig||7,117 living languages|
|24||2021||Eberhard, Simons & Fennig||7,139 living languages|