Our third article on the history of evaluation use affirms its importance in evaluation practice and related literature. It first highlights the centrality of use in the field's professionalizing documents, extant theories, and the persistence of continuing research. Next, it discusses the challenge of evaluation theories in general, including the prevalence of prescriptive theories, and provides criteria for a good descriptive use theory that even the most detailed use theory does not currently meet. The third section reviews existing use "theories," nine from Alkin's evaluation theory tree, two from the literature, and two existing influence theories. This article concludes with a discussion of research on evaluation use past and present, including the effects of competing definitions, along with thoughts for future inquiry.