This issue broaden the field s understanding of Research on Evaluation (RoE) in practice, with a focus on empirical RoE. Considering the full collection of RoE studies, it defines RoE as systematic empirical inquiry resulting in original findings or in reexaminations of existing data about the practice, methods, or profession of program evaluation. RoE inquiries address: * the inputs into evaluations, * the contexts within which evaluations are conducted, * the full range of methods and activities of evaluations, * evaluation s proximal or distal effects, or the professional issues that evaluators encounter. The inquiries include case studies, reflective narratives, studies about evaluation methods, literature reviews, oral histories, bibliometric studies, meta-evaluations, experiments, longitudinal studies, simulations, and time-series studies. This is the 148th issue in the New Directions for Evaluation series from Jossey-Bass. It is an official publication of the American Evaluation Association.