Traditional research comparing the effects of individualized instruction and conventional modes of instruction has been inconclusive. Naturalistic research dealing with the process of innovation as a critical issue was proposed as an alternative. Thus, the purpose of the study was to investigate the dynamics of change at the classroom level through identifying factors influencing change, as perceived by administrators, teachers, pupils, and investigator-observer. Ten teachers participated in an in-service experience in individualized instruction, which consisted of a series of workshops and regular classroom visits conducted by the investigator-observer. Additional data were obtained from teachers' diaries, informal pupil reactions, and interviews with a comparison group of teachers and administrators. Factors influencing change at the classroom level were identified. Naturalistic research was shown to be functional and valuable in that it suggested new patterns of organization in studies on individualized instruction, particularly the role of the pupil in educational change.