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 on Kriol since the 1990s.
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 (Segerer 2010):