This monograph addresses concerns about mathematics and science instruction and educational outcomes for Native students. The sociocultural contexts of schooling and community come together in particular ways to influence how Native children learn and, consequently, their life outcomes. It is important to look beyond the performance of individual students to the systems in which they are educated and to the historical and social influences on how mathematics and science are conceptualized and taught. Methods for implementing current mathematics and science reforms are shaped by assumptions about what children should know and be able to do. This monograph seeks to make such assumptions and the Western cultural values underlying them more explicit, and suggests that a generic approach to reform is ineffective and inequitable. Student differences with implications for teachers' choices about instructional strategies include differences in: (1) ways of knowing with regard to mathematics and science, rooted in varying world views; (2) approaches to learning and problem solving; (3) communication styles, strategies, and uses; and (4) cultural values about use and sharing of particular kinds of knowledge. Ethnoscience and ethnomathematics (forms embedded in cultural activities, the workplace, or everyday life) can serve to contextualize instruction--to provide real-life connections that make classroom theories and practices meaningful. Several examples demonstrate how such connections can be made. A set of guidelines is presented for instruction that bridges cultures and situates mathematics and science learning in meaningful contexts for Native students, as well as for all underserved students. Contains 130 references. (SV)