Bijago or Bidyogo is the language of the Bissagos Archipelago of Guinea-Bissau. Bidyogo is the "dominant mother tongue of the archipelago population", though it is not used in schooling there, a role that has been taken over by Kriol since the 1990s. There are some difficulties of grammar and intelligibility between dialects, with the Kamona dialect being unintelligible to the others.

Dialects are as follows:

The Kajoko dialect is one of the few in the world known to use a linguolabial consonant, the voiced stop to tap [d̼ ~ ɾ̼], in its basic sound system.

Bijago is highly divergent. Sapir (1971) classified it as an isolate within the West Atlantic family. However, Segerer showed that this is primarily due to unrecognized sound changes, and that Bijago is in fact close to the Bak languages. For example, the following cognates in Bijago and Joola Kasa (a Bak language) are completely regular, but had not previously been identified: