Professional development programs have been established in many academic libraries to support the research and scholarly activities of librarians. Continuous assessment can contribute to the sustainability and effectiveness of these programs. This study describes how measures of need, participation, satisfaction, and impact were employed to assess many aspects of a professional development program in a large academic library. Results from these assessments were used to justify the program to the library administration, continuously improve the program, and provide information about its benefits to current and potential participants.