A holistic approach to research design was used in this analysis of a long term, large scale professional development project held at 8 university sites in one state over a 3 year period that involved 360 teacher leaders and their principals from 180 elementary schools. The purpose of this analysis was to examine the links among professional development, teacher leaders, and change in the teaching of science and mathematics. Qualitative and quantitative data were gathered over the 3 years on a number of different aspects of the project, some of which have previously been reported. Data sources included observations, interviews, and written program documents. Detailed analyses examined models of professional development, the lead teachers' implementation of these models in schools, design and components of professional development experiences, and important factors for professional development cited by lead teachers. The qualitative methodology revealed important links, connections, and implications that emerged from the multiple data sources. Findings indicate three important categories (Content and Pedagogy, Leadership Content, Leadership Planning and Practice) that should be included in professional development. The components of these categories are identified and described and reveal new insights on professional development. Recommendations are provided for professional development that enhances school change. (Contains 46 references.) (Author/ASK)