A school improvement model intended to facilitate the implementation of a new mathematics curriculum in a large heterogeneous school district is described. The model is based primarily on the concepts and components of the Concerns-Based Adoption Model, and it includes theory and research findings from recent studies involving the role of the principal in the change process and supervisory coaching. The model gave rise to the Intervention Coaching Project, which was used to train Hillsborough County (Florida) School District administrators in the implementation of a new elementary mathematics curriculum during the fall term of 1986. Six schools participated in the project. Each school formed a coaching team consisting of the principal, curriculum specialist, and district general supervisor. Inservice training was provided to participants, and a consultant was assigned to each school. Evaluation of the model followed a traditional formative model, and involved six control schools. Interviews and questionnaires provided information on implementation and teacher attitudes; student achievement was assessed via the district's annual achievement test battery. Tentative findings indicate that the model is viable for bringing about change in the implementation of a new curriculum program. One table is included. (Author/TJH)