Mastery learning represents an increasingly 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 been a catalyst for paradigm shift from a dominant prediction-selection model to an emerging diagnostic-development model. Since Bloom's seminal publication in 1968, the preponderance of the mastery learning literature has focused on the North American experience and its sociocultural interpretations with only occasional documentation of mastery learning efforts in other parts of the world. In response to this imbalance, this paper attempts to review mastery learning efforts in the European research community over the past 25 years. Attention is given to developments in mastery learning theory and practice as documented in several European countries with a view toward acknowledging and expanding research in this area of educational psychology. (Contains 71 references.) (Author/SLD)