This paper argues that the information processing model provides a promising basis on which to build a comprehensive theory of instruction. Characteristics of the major information processing constructs are outlined including attention, encoding and rehearsal, working memory, long term memory, retrieval, and metacognitive processes, and a unifying relationship between instructional learning strategies and cognitive operations is proposed. Specifically, the locus of cognitive processing--whether heavily assumed by the instruction, activated in the learner via the instruction, or maintained in control of the learner--is explored in relation to each major cognitive processing operation. Evidence is discussed which suggests an inverse relationship between the extent to which the instruction assumes or directs cognitive processing operations and the aptitudinal strengths of learners. The implications for the instructional design and research professional for optimal assignment of cognitive processing--whether to the instruction or to the learner--is also presented. An extensive bibliography is appended. (Author/LLS)