A team at the University of Minnesota conducted the Collaboratives for Excellence in Teacher Preparation (CETP) core evaluation between 1999 and 2004. The purpose of the CETP core evaluation was to achieve consensus among CETP project leaders and project evaluators on evaluation questions; to develop, pilot, and field test evaluation instruments tied to the questions; and to collect data to document the accomplishments of the CETP projects. This chapter examines the relationship between project-level involvement in the CETP core evaluation and the use of the evaluation by project principal investigators (PIs) and evaluators. The chapter examines the tensions and trade-offs that arose from attempting to balance voluntary involvement by project PIs and evaluators in the planning and development of the evaluation with the need to collect complete and comparable data across project sites.