This document is one of 17 volumes on indigenous Mexican languages and is the result of a project undertaken by the Archivo de Lenguas Indigenas de Mexico. This volume contains information on Mayo, an indigenous language of Mexico spoken in Los Capomos, in the state of Sinaloa. The objective of collecting such a representative sampling of the linguistic richness of the region was to store it for typological and historic comparisons. To gather data, questionnaires designed to elicit responses that would reveal the linguistics, vocabulary, grammar, and syntax of the language were administered to the indigenous people of the area. This work is the first systematic attempt to create source material of such magnitude. Basic information has been collected that is directly useful and will serve as a departure point for detailed study. Each volume deals with the phonology, morphophonemics, grammar, and vocabulary of the language. Literature is included with Spanish translations, as is actual dialogue. Numerous sentences are analyzed. (CK)