The concept of mediated learning is examined, focusing on the work of L. Vygotsky (1896-1934) and R. Feuerstein (born 1921). Mediated learning is the subtle social interaction between teacher and learner in the enrichment of the student's learning experience. Both theorists take a strong sociological approach to the development of intelligence and cognition; their socio-cultural psychology seeks to place human beings in a larger biological context. Mediation for learning is an important key to survival and success. Feuerstein makes an important distinction between functions (a Vygotskian concept) that serve as prerequisites of cognition, and cognitive operations, which correspond more or less to the Piagetian notion of intellectual operations. Empirical studies were conducted to apply each theorist's view. The Vygotskian study examined the discovery of contradictions in pictured situations for 19 young adult Russian immigrants to Israel who were special education teachers. The Feuerstein-based study was conducted between January and June of 1991 and examined thinking among 151 American minority middle grade (grades 5 through 7) students, 29 of whom were in special education. In both studies, the use of tools of instruction, embedded in scaffolding or apprenticeship models of learning, highlighted tasks of internalization of ability through mediation. Recognizing the importance of mediated learning could cause the teacher's role to move from provider of knowledge to learning facilitator, as the student becomes self-regulated, independent, and creative. There is a 57-item list of references. (SLD)