Consistent with definitions of theory as offered by Skinner and Bruner, and based on psychological and neurophysiological evidence for a cognitive hierarchy as propounded by eminent psychologists, the structure process theory has validity in constructing a model of reading instruction. The appropriateness of model construction arises from the nature of reading as a cumulative process which can be divided into specific subskills and abilities. A basic concept is the ordinal nature of human development as opposed to normative concepts. Therefore, this theory rejects normative data such as IQ scores and grade level equivalents when diagnosing reading ability. Instruction which is individualized to the extent that it (1) proceeds from diagnosis of what the child can do, (2) observes the hierarchical arrangement of reading skills, (3) matches these two procedures in order to control change, and (4) continues to diagnose in order to obtain optimum match can be said to be based on the structure process theory. A bibliography is included. (DH)