Book excerpt: The Mbugu (or Ma'á) language (Tanzania) is one of the few genuine mixed languages, reputedly combining Bantu grammar with Cushitic vocabulary. In fact the people speak two languages: one mixed and one closely related to the Bantu language Pare. This book is the first comprehensive description of these languages. It shows that these two languages share one grammar while their lexicon is parallel. In the distant past the people shifted from a Cushitic to a Bantu language and in the process rebuilt a language of their own that expresses their separate ethnic identity in a Bantu environment. This linguistic history is explained in the context of the intricate history of the people. The discussion of the processes that were involved in the formation of Ma'a/Mbugu is extremely relevant for both creole studies and for contact linguistics in general.