Current research and though regarding the relationship of individual difference (ID) factors to achievement in the basic skills is reviewed. Four major categories and nine subcategories of ID factors are defined and serve as the framework for the review: status factors (age, sex, and race, ethnic group, and socioeconomic status); intelligence factors (IQ and specific intellective factors, and perceptual factors); affective factors (attitudes and personality factors); and process factors (cognitive styles and cognitive strategies). Within each section of the paper, an attempt is made to examine research on IDs from the perspective of identifying strategies of instructional intervention that might be employed to accomodate or reduce achievement-related learner differences. The review emphasizes that factors which describe variations in student performance on learning tasks are more useful for the design of adaptive instructional practices than are factors that describe psychometric traits of learners. Accordingly, the promises inherent in continued research on process factors are emphasized. (A bibliography is appended.) (Author/GDC)