A PhD dissertation about language shift and maintenance in Iyasa-speaking communities in Cameroon, through a sociolinguistic language documentation framework. The dissertation includes information about language vitality, Iyasa speakers' perceptions of language use and endangerment, and the linguistic, social and historical context of the Iyasa language, as well as a quantitative sociolinguistic study of language variation and shift. It also includes a description of a youth-driven language revitalization program, Iyasa Éboó.