Theories of human development and learning provide an essential framework in which to understand the mechanisms involved in the process of formal instruction as a specific form of teaching and learning in the school setting. The sociocultural theory of development, founded on the works of Lev Vygotsky, espouses the view that social interaction among two or more people is the greatest motivating force in human development. Communication, via the use of language, provides one of the most effective means of social interaction. By collaborating toward a common cultural goal, people co-construct new knowledge by building on each participant's contribution. Based on the main tenets of sociocultural theory, the following eight interrelated principles for instruction are presented, namely, that it should be: mediated; discursive; collaborative; responsive; contextualized; activity-oriented; developmental; and integrated. (Contains 1 figure.)