This paper presents the theories of L.S. Vygotsky as a conceptual framework for implementing instruction that supports concept development and promotes higher level thinking skills in students. Three major components (i.e., language, scientific and spontaneous concepts, and the zone of proximal development) of Vygotsky's socio-cultural-historical theories of learning are considered. The relationship of these components to the commonalities evidenced in the mathematics and science standards that suggest the efficacy of integrated curricular activity are then discussed. Next, the characteristics of computer-mediated communication (CMC) are presented, and the rationale for its use in an integrated mathematics and science curriculum is discussed. Finally, a current project is outlined that uses CMC as a facilitating technology for an integrated fifth-grade mathematics and science curriculum that is consistent with both a Vygotskian approach to learning and the mathematics and science standards. (Contains 41 references.) (MES)