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,...