As a basis for developing guidelines for educational courseware development and for teacher education in the instructional uses of microcomputers, this study was planned to examine relationships among 60 successful computer-using teachers' attitudes toward computers, their knowledge of the subject matter taught, and their uses of microcomputers for instruction. Preliminary results indicate that districts vary greatly in microcomputer implementation, although little variability in implementation strategies has been found among principals. Almost all principals favor instructional use of microcomputers and give teachers much of the responsibility for expanding the school computer program, although few principals have much microcomputer-related knowledge. Teachers coordinate computer uses with other instructional materials and with the curriculum, though the type or degree of coordination varies for different reasons. Three phenomena seem to characterize successful integration of computers in instruction: individualized assignments, group computer activities, and teachers' examination of feedback on students' computer activities. Microcomputers are more likely to be integrated into ongoing instruction--and used in different ways--when they are inside or directly accessible to classrooms. Elementary schools are more apt to put microcomputers inside classrooms, while secondary schools frequently favor lab type arrangements. However, differences among teachers seem most prominent in how computers are used for instruction. Courseware knowledge rather than hardware and programming knowledge appears most important for teachers who wish to vary modes of instruction and student grouping, and to match courseware to individual students. (LMM)