Mastery learning represents a prolific area of research in educational psychology that encompasses two principal characteristics: (1) an optimistic set of assumptions regarding the capability of students to learn if alterable variables comprising the conditions of learning are optimized; and (2) an array of adaptive instructional procedures predicated on the medical model of diagnostic-prescriptive intervention. From both theoretical and practical perspectives, mastery learning has served as a catalyst for a paradigm shift from a dominant prediction-selection model to an emerging diagnostic-developmental model. Since B. S. Bloom's seminal publication in 1968, the preponderance of mastery learning literature has focused on the North American experience. In response to the lack of a worldwide perspective on mastery learning, this paper attempts to operationalize the international dimensions of mastery learning by specifying its essential meaning and defining characteristics, its current status in the international professional literature, and needed initiatives for advancing mastery learning efforts internationally. These efforts concentrate on: (1) establishing communication networks; (2) determining topical areas of focus; and (3) formulating research and development methodologies. (Contains 117 references.) (SLD)