Four school boards in Ontario, Canada, were selected for intensive case studies to examine the models, policies, procedures, and practices used to stimulate, support, coordinate, and assess the effectiveness of curriculum changes within their jurisdictions. The data collection consisted of (1) documents such as organizational charts, implementation models, job descriptions, task force and other reports; (2) interviews conducted with 32 supervisory officers, 37 curriculum consultants, 16 principals, and 32 teachers; and (3) questionnaires completed by 59 consultants. The report provides descriptions of the four models, examination of the models as practiced, identification of factors facilitating and inhibiting implementation of the models, a more focused examination at the school level of a specific curriculum innovation selected by each board, and an assessment of the effectiveness and outcomes of the models. The report concludes with an analysis of planned change in perspective by considering the recent literature on the role of school systems in change, by reviewing current trends and practices in Ontario, and by formulating a number of lessons and recommendations for developing more effective models, practices, and procedures for planning and implementing curriculum improvements. The report contains 8 figures and 16 tables, and a 29-item bibliography is appended. (MLF)