| Country | Languages |
| Cook Islands | English (official), Maori |
| Coral Sea Islands | void |
| Costa Rica | Spanish (official), English |
| Cote d'Ivoire | French (official), 60 native dialects of which Dioula is the most widely spoken |
| Croatia | Croatian (official) 96.1%, Serbian 1%, other and undesignated (including Italian, Hungarian, Czech, Slovak, and German) 2.9% (2001 census) |
| Cuba | Spanish (official) |
| Curacao | Papiamentu (a Spanish-Portuguese-Dutch-English dialect) 81.2%, Dutch (official) 8%, Spanish 4%, English 2.9%, other 3.9% (2001 census) |
| Cyprus | Greek (official), Turkish (official), English |
| Czech Republic | Czech 94.9%, Slovak 2%, other 2.3%, unidentified 0.8% (2001 census) |
| Denmark | Danish, Faroese, Greenlandic (an Inuit dialect), German (small minority) note: English is the predominant second language |
| Dhekelia | English, Greek |
| Djibouti | French (official), Arabic (official), Somali, Afar |
| Dominica | English (official), French patois |
| Dominican Republic | Spanish (official) |
| Ecuador | Spanish (official), Amerindian languages (especially Quechua) |
| Egypt | Arabic (official), English and French widely understood by educated classes |
| El Salvador | Spanish (official), Nahua (among some Amerindians) |
| Equatorial Guinea | Spanish (official) 67.6%, other (includes French (official), Fang, Bubi) 32.4% (1994 census) |
| Eritrea | Tigrinya (official), Arabic (official), English (official), Tigre, Kunama, Afar, other Cushitic languages |
| Estonia | Estonian (official) 67.3%, Russian 29.7%, other 2.3%, unknown 0.7% (2000 census) |