The techniques and effectiveness of systems for adjusting the pace, content, sequence, and style of instruction to fit the needs of individual learners are briefly reviewed. These systems are all designed to function in group instructional settings. They may be separated into print-oriented approaches (programmed instruction, personalized system of instruction, audio-tutorial approach, and individually guided education) and computer-oriented approaches (individually prescribed instruction, adaptive learning environments model, program for learning in accordance with needs, the strands approach, optimization of instruction, and intelligent computer-assisted instruction). The primary task of these and similar systems is to replace the two standard deviations of achievement that may be lost by grouping students for instruction rather than providing a single teacher for each student in one-on-one, individualized instructional settings. Difficulty in accomplishing this task appears to lie primarily with the costs and increased workload that individualization requires. (Contains 43 references.) (Author/SLD)