Implementation Fidelity Affects the Degree of Change in Teacher Practice.

School improvement that depends on professional development as a primary means for implementing effective instructional practice requires deliberate attention to implementation fidelity of both the content and process of professional development, the ongoing development of professional developers, and the measurement of implementation over time. When schools have high-fidelity implementation of the professional development principles of both professional development content and process, teachers have significantly higher frequency of implementation of instructional practices aligned with the reform program than schools that were low in implementation or those that had high levels in one and low levels in another.