The language competency of members of the Pascua Yaqui Tribe encompasses, to varying degrees, the Yaqui language as well as community dialects of Spanish and English. This unique trilingual pattern has been functional for survival needs but has also been a barrier to educational achievement where competency in standard forms of Spanish and English is required. This paper provides historical background on the Yaquis and describes tribal efforts and programs to meet the language development needs of Yaqui communities. Historical sections discuss the Yaqui homeland in Sonora state (Mexico), incorporation of Spanish words and grammatical structures into Yaqui, refugee migrations to southern Arizona and marginalization from Anglo and Mexican communities, development of a nonstandard English dialect influenced by Yaqui and Spanish forms, educational discrimination in Arizona public schools, a 1973 lawsuit over improper special education placements of Yaqui children, and a trilingual/tricultural Yaqui community school operated during the 1970s-80s by the activist Guadalupe Organization. In 1981 the Tucson Unified School District and the Pascua Yaqui Tribe agreed to develop the Yaqui/English Bilingual Education Project, and in 1984 the tribal council adopted a language policy affirming the Yaqui language as an integral part of all school curricula. The Yaqui Family Literacy Partnership Program was federally funded in 1988 and led to an international conference of Arizona and Sonora Yaquis. A recent family literacy program, Project Kaateme, incorporates a parent-as-tutor strategy based on a nondeficit family approach. Project staff also teach Yaqui second-language classes for adults and preschoolers. Contains 16 references. (SV)