The last quarter of a century has seen significant progress in the identification and assessment of individual difference variables and an increasing awareness of the importance of seeing variables in the context of others, both in their effect on one another and their interactive effect on educational performance. Several challenges must now be met in order to improve practical educational performance. These include: the development of refined methods of determining and assessing the primary variables affecting performance and of distinguishing them from secondary variables; the construction of a coherent model of the interactive effect of these variables on performance; the clarification of the nature of educational objectives; and the refinement of means of realistically managing individual differences. Individual difference research also has implications for experimental studies in education, since if individual variables are not included the effects of intervention treatments could be obscured. A scheme of systematic research to move this area forward is proposed.