| msqCaac | msq | Austronesian | | | 6b · Threatened |
| cjpCabécar | cjp | Chibchan | | | 6b · Threatened |
| cbbCabiyari | cbb | Upper Amazon Arawakan | | 270 | 7 · Shifting |
| ccrCacaopera | ccr | Misumalpan | | | 10 · Extinct |
| rocCacgia Roglai | roc | — | | | 6a · Vigorous |
| cadCaddo | cad | Caddoan | | | 8a · Moribund |
| agtCagayan Agta | agt | Austronesian | | | 5 · Developing |
| ktwCahto | ktw | Na-Dene | | | 9 · Dormant |
| cahCahuarano | cah | Saparo–Yawan | | | 10 · Extinct |
| chlCahuilla | chl | Uto-Aztecan | | 6 | 8b · Nearly Extinct |
| qvcCajamarca QuechuaKashamarkapa runashimi | qvc | Quechua | | 30,000 | 6b · Threatened |
| frcCajun FrenchFrançais cadien | frc | Indo-European | | | 7 · Shifting |
| ckyCakfem-Mushere | cky | Afroasiatic | | | 6a · Vigorous |
| tbkCalamian Tagbanwa | tbk | Austronesian | | | 5 · Developing |
| rmqCaló | rmq | Indo-European | | 60,000 | 5 · Developing |
| cluCaluyanon | clu | — | | | 5 · Developing |
| wesCameroon Pidgin | wes | — | | 2 m | 3 · Wider Communication |
| rabCamling | rab | Sino-Tibetan | | | 6b · Threatened |
| cmlCampalagianbahasa Campalagian | cml | Austronesian | | | 6a · Vigorous |
| sroCampidanese | sro | Indo-European | | | 6b · Threatened |
| kbhCamsá | kbh | — | | 4,000 | 5 · Developing |
| qxrCañar Highland Quichua | qxr | Quechua | | | 6b · Threatened |
| cbuCandoshi-Shapra | cbu | — | | 1,120 | 5 · Developing |
| cazCanichana | caz | — | | | 9 · Dormant |
| idbCannanore Indo-Portuguese creole | idb | — | | 8 | Severely endangered |
| kaqCapanahua | kaq | Pano-Tacanan | | | 7 · Shifting |
| keaCape Verdean Creolekabuverdianu | kea | — | | 871,000 | 1 · National |
| cpsCapiznonKinapisnon | cps | Austronesian | | 640,000 | 6a · Vigorous |
| cpgCappadocian Greek | cpg | Indo-European | | 2,800 | 8b · Nearly Extinct |
| cotCaquinte | cot | Southern Maipuran | | 500 | 5 · Developing |
| caqCar | caq | Austroasiatic | | 37,000 | 3 · Wider Communication |
| cfdCara | cfd | Niger–Congo | | | 7 · Shifting |
| cbyCarabayo | cby | — | | 150 | 6b · Threatened |
| cbcCarapana | cbc | Tucanoan | | 482 | 5 · Developing |
| xcrCarian | xcr | Indo-European | | | |
| carCarib | car | Cariban | +2 | 10,000 | 6b · Threatened |
| hnsCaribbean Hindustani | hns | Indo-European | | 165,000 | |
| jvnCaribbean Javanese | jvn | Austronesian | | 60,000 | 5 · Developing |
| cbdCarijonatsahá | cbd | — | | 10 | 8b · Nearly Extinct |
| calCarolinianRefaluwasch | cal | Austronesian | | 5,700 | 4 · Educational |
| rmcCarpathian Romani | rmc | Indo-European | | 150,000 | 5 · Developing |
| crxCarrier | crx | Na-Dene | | 1,270 | 7 · Shifting |
| cbrCashibo-Cacataibo | cbr | Pano-Tacanan | | 1,200 | 5 · Developing |
| cbsCashinahua | cbs | Pano-Tacanan | | 1,200 | 5 · Developing |
| ascCasuarina Coast Asmat | asc | — | | | 6a · Vigorous |
| catCatalancatalà | cat | Indo-European | +1 | 10 m | 2 · Provincial |
| cscCatalan Sign Languagellengua de signes catalana | csc | — | | | 6b · Threatened |
| chcCatawba | chc | Hoka-Sioux | | | 9 · Reawakening |
| ctoCatio | cto | Choco | | 15,000 | 6a · Vigorous |
| xagCaucasian Albanian | xag | Northeast Caucasian | | | |
| ckzCauque Mayan | ckz | — | | | 7 · Shifting |
| cavCavineña | cav | Pano-Tacanan | | | 6b · Threatened |
| cayCayugaGayogo̱hó꞉nǫʼ | cay | Iroquoian | | 55 | 8a · Moribund |
| xcyCayuse | xcy | Plateau Penutian | | | Extinct |
| cybCayuvava | cyb | — | | | 9 · Dormant |
| rukCe | ruk | — | | | 6a · Vigorous |
| sefCebaara | sef | Niger–Congo | | | 5 · Developing |
| cebCebuanoSinugboanon | ceb | Austronesian | | 15.9 m | 3 · Wider Communication |
| xceCeltiberian | xce | Indo-European | | | Extinct |
| camCèmuhî | cam | Austronesian | | | 6b · Threatened |
| esuCentral Alaskan Yup'ik | esu | — | | 16,900 | 6b · Threatened |
| cnsCentral Asmat | cns | — | | | 6b · Threatened |
| tzmCentral Atlas TamazightTmaziɣt n waṭlas anammas | tzm | — | | 17 m | 6a · Vigorous |
| awuCentral Awyu | awu | Trans–New Guinea | | | 6a · Vigorous |
| bcaCentral Bai | bca | Sino-Tibetan | | | 6a · Vigorous |
| zbcCentral Berawan | zbc | Austronesian | | | 8a · Moribund |
| bclCentral BikolBikol Sentral | bcl | Austronesian | | 2.5 m | 3 · Wider Communication |
| grvCentral Grebo | grv | Niger–Congo | | | 6a · Vigorous |
| hmcCentral Huishui Hmong | hmc | Hmong–Mien | | | 6a · Vigorous |
| kylCentral Kalapuya | kyl | — | | | 10 · Extinct |
| kncCentral Kanuri | knc | Nilo-Saharan | +1 | 9.3 m | 3 · Wider Communication |
| ckbCentral Kurdishکوردیی ناوەندی | ckb | Indo-European | | 7.2 m | 2 · Provincial |
| pseCentral Malay | pse | Austronesian | | | 6a · Vigorous |
| hmmCentral Mashan Hmong | hmm | Hmong–Mien | | | 6a · Vigorous |
| melCentral Melanau | mel | Austronesian | | | 6b · Threatened |
| nhnCentral Nahuatl | nhn | Uto-Aztecan | | 40,000 | 6b · Threatened |
| ncbCentral Nicobarese | ncb | Austroasiatic | | | 5 · Developing |
| ojcCentral Ojibwa | ojc | Algic | | | 6b · Threatened |
| otsCentral Otomi | ots | Central American Indian languages | | | 5 · Developing |
| plcCentral Palawano | plc | Austronesian | | | 5 · Developing |
| pbsCentral Pame | pbs | Central American Indian languages | | | 6a · Vigorous |
| pstCentral Pashto | pst | Indo-European | | 6.5 m | 6a · Vigorous |
| pooCentral Pomo | poo | Pomoan | | | 9 · Dormant |
| smlCentral Sama | sml | Austronesian | | | 4 · Educational |
| essCentral Siberian YupikAkuzipigestun | ess | — | | 1,800 | 5 · Developing |
| csmCentral Sierra Miwok | csm | Yok-Utian | | 12 | 8b · Nearly Extinct |
| tgtCentral Tagbanwa | tgt | Austronesian | | | 8b · Nearly Extinct |
| eboCentral Teke | ebo | Niger–Congo | | | 6b · Threatened |
| becCeve | bec | Niger–Congo | | | 6a · Vigorous |
| cbiCha'palaa | cbi | Barbacoan | | 10,000 | 6b · Threatened |
| qukChachapoyas Quechua | quk | Quechua | | 7,000 | 4 · Educational |
| caoChácobo | cao | Pano-Tacanan | | 600 | 5 · Developing |
| shuChadian Arabicلهجة تشادية | shu | — | +4 | 2.6 m | 3 · Wider Communication |
| chgChagatai | chg | Turkic | | | 10 · Extinct |
| cliChakali | cli | Niger–Congo | | | 6b · Threatened |
| ckmChakavian | ckm | Indo-European | | | |
| ccpChakmaChangmha Bhach | ccp | Indo-European | | 326,000 | 5 · Developing |
| cllChala | cll | Niger–Congo | | | 6b · Threatened |
| cldChaldean Neo-Aramaic | cld | Afroasiatic | | | 7 · Shifting |
| tgfChali | tgf | Bodish | | | 6b · Threatened |
| cjaChamꨌꩌ | cja | Austronesian | | 400,000 | |
| cegChamacocoIshír | ceg | — | | 2,000 | 6a · Vigorous |
| cjiChamalal | cji | Northeast Caucasian | | 500 | 6b · Threatened |
| ndiChamba Leko | ndi | Niger–Congo | | | 5 · Developing |
| cdhChambealiचम्बयाली | cdh | — | | | 6a · Vigorous |
| canChambri | can | Ramu–Lower Sepik | | | 6a · Vigorous |
| cmiChami | cmi | Choco | | | 5 · Developing |
| cccChamicuro | ccc | — | | 2 | 9 · Dormant |
| chaChamorro | cha | Austronesian | | 64,300 | 1 · National |
| cajChané | caj | Southern Maipuran | | | Extinct |
| nbcChang | nbc | — | | | 5 · Developing |
| cgaChangriwa | cga | Yuat | | | 6a · Vigorous |
| chxChantyal | chx | Bodish | | | 6b · Threatened |
| craChara | cra | — | | | 6a · Vigorous |
| cdnChaudangsi | cdn | Bodish | | | 6b · Threatened |
| crvChaura | crv | Austroasiatic | | | 6b · Threatened |
| cbkChavacano | cbk | Indo-European | | 431,000 | 4 · Educational |
| cbtChayahuita | cbt | Jivaroan-Cahuapanan | | 14,000 | 5 · Developing |
| xtbChazumba Mixtec | xtb | Central American Indian languages | | | 8a · Moribund |
| cheChechenНохчийн мотт | che | Northeast Caucasian | +2 | 1.4 m | 2 · Provincial |
| mrnCheke Holo | mrn | Austronesian | | | 5 · Developing |
| cjnChenapian | cjn | Sepik | | | 6b · Threatened |
| cdeChenchu | cde | Dravidian | | | 6a · Vigorous |
| cdmChepang | cdm | Sino-Tibetan | | 36,807 | 6b · Threatened |
| ycpChepya | ycp | Sino-Tibetan | | | 7 · Shifting |
| cwgCheq Wong | cwg | Austroasiatic | | | 6b · Threatened |
| cpnCherepon | cpn | Niger–Congo | | | 6a · Vigorous |
| chrCherokeeᏣᎳᎩ ᎧᏬᏂᎯᏍᏗ | chr | Iroquoian | | 12,300 | 8a · Moribund |
| ychChesu | ych | Sino-Tibetan | | | 7 · Shifting |
| ctcChetco | ctc | — | | | 9 · Dormant |
| nyaChewaChilankhulo cha Chichewa | nya | Niger–Congo | +1 | 12 m | 3 · Wider Communication |
| chyCheyenneTsêhesenêstsestôtse | chy | Algic | | 2,400 | 8a · Moribund |
| hneChhattisgarhi | hne | Indo-European | | 16.3 m | 4 · Educational |
| csdChiangmai Sign Language | csd | — | | | 8a · Moribund |
| cipChiapanec | cip | Central American Indian languages | | | 9 · Dormant |
| sehChibarwe | seh | Niger–Congo | | | 5 · Developing |
| chbChibchaMuysccubun | chb | Chibchan | | | 9 · Dormant |
| peiChichimeca Jonaz | pei | Central American Indian languages | | | 7 · Shifting |
| cicChickasawChikashshanompa' | cic | Muskogean | | 75 | 8a · Moribund |
| vmvChico | vmv | Maiduan | | | 10 · Extinct |
| cobChicomuceltec | cob | Central American Indian languages | | | 9 · Dormant |
| miiChigmecatitlán Mixtec | mii | Central American Indian languages | | | 6b · Threatened |
| csgChilean Sign Language | csg | — | | 21,000 | 5 · Developing |
| clhChilisso | clh | — | | | 6b · Threatened |
| zohChimalapa Zoque | zoh | Mixe–Zoque | | | 6b · Threatened |
| casChimane | cas | — | | 5,300 | 6b · Threatened |
| cidChimariko | cid | — | | | 10 · Extinct |
| qugChimborazo Highland Quichua | qug | Quechua | | | 5 · Developing |
| cbgChimila | cbg | Chibchan | | | 6b · Threatened |
| bxuChina Buriat | bxu | Mongolic | | 65,000 | 7 · Shifting |
| cihChinali | cih | Indo-European | | 220 | 6b · Threatened |
| chjChinantec of Ojitlán | chj | Central American Indian languages | | | 5 · Developing |
| chzChinantec of Ozumacín | chz | Central American Indian languages | | | 6b · Threatened |
| cntChinantec of Tepetotutla | cnt | Central American Indian languages | | | 6a · Vigorous |
| zhoChinese汉语 | zho | Sino-Tibetan | | 1.30 bn | |
| cpiChinese Pidgin English | cpi | — | | | 6b · Threatened |
| cslChinese Sign Language中国手语 | csl | — | | | 5 · Developing |
| chnChinook JargonChinuk Wawa | chn | — | | 1 | 9 · Dormant |
| ctnChintang | ctn | Sino-Tibetan | | | 6b · Threatened |
| capChipayaChipay taqu | cap | — | | 1,800 | 5 · Developing |
| chpChipewyanDëne Sųłıné Yatıé | chp | Na-Dene | | 11,325 | 6b · Threatened |
| ciwChippewaAnishinaabemowin | ciw | Algic | | | 7 · Shifting |
| maqChiquihuitlán Mazatec | maq | Central American Indian languages | | | 6b · Threatened |
| caxChiquitano | cax | Macro-Jê | | 2,400 | 6b · Threatened |
| cdfChiru | cdf | Sino-Tibetan | | | 5 · Developing |
| ctmChitimacha | ctm | — | | | 9 · Dormant |
| ctgChittagonian | ctg | Indo-European | | 13 m | 3 · Wider Communication |
| theChitwania Tharu | the | Indo-European | | | 5 · Developing |
| zpcChoapan Zapotec | zpc | Central American Indian languages | | | 6b · Threatened |
| cgkChocangaca | cgk | Southern Tibetic | | | 6a · Vigorous |
| cozChocho | coz | Central American Indian languages | | | 8b · Nearly Extinct |
| choChoctawChahta anumpa | cho | Muskogean | | 9,200 | 6b · Threatened |
| nriChokri | nri | Sino-Tibetan | | | 4 · Educational |
| cjkChokwe | cjk | — | | | 3 · Wider Communication |
| ctuCh’ol | ctu | Central American Indian languages | | 180,000 | 5 · Developing |
| chtCholónSeeptsá | cht | — | | | 10 · Extinct |
| cogChong | cog | Austroasiatic | | | 7 · Shifting |
| cdaChoni | cda | — | | | 7 · Shifting |
| chfChontal Maya | chf | Central American Indian languages | | | 6a · Vigorous |
| cohChonyi | coh | Niger–Congo | | | 6a · Vigorous |
| cceChopi | cce | Niger–Congo | | | 5 · Developing |
| momChorotega | mom | Central American Indian languages | | | 9 · Dormant |
| caaCh’orti’Ch'orti' | caa | Central American Indian languages | | 30,000 | 5 · Developing |
| nctChothe | nct | — | | | 6a · Vigorous |
| qvyChoyo | qvy | Sino-Tibetan | | | 6b · Threatened |
| crwChrau | crw | Austroasiatic | | | 6b · Threatened |
| cjeChru | cje | Austronesian | | | 6b · Threatened |
| cvgChug | cvg | Sino-Tibetan | | | 6b · Threatened |
| cacChujKoti' | cac | Central American Indian languages | | 43,370 | 5 · Developing |
| cuhChuka | cuh | Niger–Congo | | | 6a · Vigorous |
| cktChukchiԒыгъоравэтԓьэн йиԓыйиԓ | ckt | — | | 5,100 | 6b · Threatened |
| cuwChukwa | cuw | Sino-Tibetan | | | 8b · Nearly Extinct |
| curChulung | cur | Sino-Tibetan | | | 6b · Threatened |
| clwChulym | clw | Turkic | | 44 | 8a · Moribund |
| ncuChumburung | ncu | Niger–Congo | | | 5 · Developing |
| cnqChung | cnq | — | | | 5 · Developing |
| cdjChurahi | cdj | — | | | 6a · Vigorous |
| chuChurch SlavonicⰔⰾⱁⰲⱑⱀⱐⱄⰽⱏ ⱗⰸⱏⰺⰽⱏ | chu | Indo-European | +14 | | 6b · Threatened |
| scbChut | scb | Austroasiatic | | 4,279 | 7 · Shifting |
| chkChuukesefóósun Chuuk | chk | Austronesian | | 51,330 | 2 · Provincial |
| xcvChuvan | xcv | Uralic | | | Extinct |
| chvChuvashЧăваш чĕлхи | chv | Turkic | +1 | 738,070 | 2 · Provincial |
| chwChuwabu | chw | Niger–Congo | | | 5 · Developing |
| cibCi-Gbe | cib | Niger–Congo | | | 6a · Vigorous |
| ciaCia-CiaBahasa Ciacia | cia | Austronesian | | 80,000 | 6a · Vigorous |
| cklCibak | ckl | Afroasiatic | | | 6a · Vigorous |
| cimCimbrian | cim | Indo-European | | 400 | 6b · Threatened |
| cieCineni | cie | — | | | 6b · Threatened |
| cinCinta Larga | cin | Tupian | | | 6a · Vigorous |
| awcCipu | awc | Niger–Congo | | | 6a · Vigorous |
| xcgCisalpine Gaulish | xcg | Indo-European | | | |
| txtCitak | txt | — | | | 5 · Developing |
| tgdCiwogai | tgd | — | | 2,000 | 6b · Threatened |
| emyClassic Maya | emy | Central American Indian languages | | | |
| xclClassical Armenianգրաբար | xcl | Indo-European | | | |
| lzhClassical Chinese文言文 | lzh | Sino-Tibetan | | | |
| myzClassical Mandaic | myz | Afroasiatic | | | 9 · Second language only |
| cmgClassical Mongolian | cmg | Mongolic | | | |
| nciClassical NahuatlNāhuatlahtōlli | nci | Uto-Aztecan | | | |
| nwcClassical Newariपुलाङ्गु नेपाल भाय् | nwc | Sino-Tibetan | | | |
| csiCoast Miwok | csi | Yok-Utian | | | 9 · Dormant |
| kzjCoastal Kadazan | kzj | Austronesian | | 200,000 | |
| kjcCoastal Konjo | kjc | Austronesian | | | 6b · Threatened |
| nazCoatepec Nahuatl | naz | Uto-Aztecan | | 1,400 | 7 · Shifting |
| codCocama | cod | Tupian | | 250 | 8a · Moribund |
| cojCochimí | coj | Hoka-Sioux | | | 9 · Dormant |
| cocCocopah | coc | Hoka-Sioux | | | 7 · Shifting |
| coaCocos Malay | coa | Austronesian | | | 6a · Vigorous |
| crdCoeur d'Alene | crd | Salishan | | 4 | 8b · Nearly Extinct |
| conCofán | con | — | | 1,700 | 5 · Developing |
| liwColbahasa Col | liw | Austronesian | | | 6a · Vigorous |
| zlmcolloquial Malay | zlm | Austronesian | +1 | | 3 · Wider Communication |
| csnColombian Sign Language | csn | — | | | 5 · Developing |
| gctColonia Tovar | gct | Indo-European | | | 7 · Shifting |
| uteColorado River Numic | ute | Uto-Aztecan | | | 6b · Threatened |
| colColumbia-Moses | col | Salishan | | | 8b · Nearly Extinct |
| comComancheNʉmʉ Tekwapʉ̲ | com | Uto-Aztecan | | 915 | 8a · Moribund |
| cfgComo Karim | cfg | — | | | 6a · Vigorous |
| cooComox | coo | Salishan | | 40 | 8a · Moribund |
| swcCongo Swahili | swc | Niger–Congo | | 9.1 m | 2 · Provincial |
| rarCook Islands MāoriMāori Kūki 'Āirani | rar | Austronesian | | 17,500 | 6b · Threatened |
| cncCôông | cnc | Sino-Tibetan | | | 6a · Vigorous |
| zocCopainalá Zoque | zoc | Mixe–Zoque | | | 6a · Vigorous |
| trcCopala Triqui | trc | Central American Indian languages | | | 5 · Developing |
| copCopticϯⲙⲉⲧⲣⲉⲙⲛ̀ⲭⲏⲙⲓ | cop | Afroasiatic | | | 9 · Second language only |
| corCornishKernowek | cor | Indo-European | | 600 | 9 · Reawakening |
| cosCorsicancorsu | cos | Indo-European | | 151,000 | 4 · Educational |
| csrCosta Rican Sign Language | csr | — | | | 5 · Developing |
| mtaCotabato Manobo | mta | Austronesian | | | 5 · Developing |
| cowCowlitz | cow | Salishan | | | 9 · Dormant |
| pbfCoyotepec Popoloca | pbf | Central American Indian languages | | | 8a · Moribund |
| creCreeᐃᔨᔨᐤ ᐊᔨᒧᐎᓐ' | cre | — | | 10,875 | |
| crhCrimean TatarQırımtatar tili | crh | Turkic | +3 | 552,740 | 5 · Developing |
| hrvCroatianhrvatski jezik | hrv | Indo-European | +8 | 7 m | 1 · National |
| csqCroatian Sign Languagehrvatski znakovni jezik | csq | — | | 13,000 | 5 · Developing |
| croCrowApsáalooke aliláau | cro | Hoka-Sioux | | 3,000 | 6b · Threatened |
| crzCruzeño | crz | Chumashan | | | 9 · Dormant |
| csfCuban Sign Language | csf | — | | | 6a · Vigorous |
| cubCubeopãmié | cub | Tucanoan | | 6,300 | 3 · Wider Communication |
| cuiCuiba | cui | Guajiboan | | 2,900 | 5 · Developing |
| cuyCuitlatec | cuy | — | | | 10 · Extinct |
| culCulina | cul | Arawan | | 3,900 | 6b · Threatened |
| cuoCumanagoto | cuo | Cariban | | 112 | 9 · Dormant |
| cuqCun | cuq | Kra–Dai | | | 6a · Vigorous |
| cupCupeño | cup | Uto-Aztecan | | | 9 · Dormant |
| kpcCurripaco | kpc | — | | 4,000 | 5 · Developing |
| quzCusco Quechua | quz | Quechua | | 1.5 m | 3 · Wider Communication |
| cclCutchi-Swahili | ccl | Niger–Congo | | | 6a · Vigorous |
| xtuCuyamecalco Mixtec | xtu | Central American Indian languages | | | 6b · Threatened |
| cyoCuyononKoyonon | cyo | Austronesian | | 120,000 | 5 · Developing |
| bwyCwi Bwamu | bwy | Niger–Congo | | | 6a · Vigorous |
| acyCypriot Arabic | acy | Afroasiatic | | 140 | 7 · Shifting |
| cesCzechčeština | ces | Indo-European | | 10.7 m | 1 · National |
| cseCzech Sign Language | cse | — | | | 5 · Developing |