In an examination of the effects of timing of feedback on student learning, participants were randomly assigned to complete five introductory course tests using either control (Scantron form) or one of three feedback (end-of-test, 24-hr delay, immediate) procedures. A cumulative final examination with 50 new items and 10 items repeated from each course test was used to assess retention during the academic semester. Fifty final examination items, administered at postcourse intervals of 3, 6, 9, and 12 months, were used to measure longer-term retention. The provision of feedback at either the end of a test or after a 24-hr delay, relative to control procedures, increased retention for 3 to 5 weeks during the semester. Robust enhancement of retention at all intervals was observed only when immediate feedback was provided. The magnitude of the immediate feedback effect indicates that students benefit from affirmation of correct responding and notification of incorrect responding during classroom tests and suggests noteworthy potential for creating learnable moments during which students validate and self-correct their knowledge stores.General education and introductory courses expose students to the foundations of an academic discipline. The broadening of the content areas that define academic disciplines, and the integration of multimedia resources into the teaching process, markedly increase the breadth of and depth at which concepts can be presented to enhance traditional lecture materials. Indeed, these changes have prompted many departments to develop a two-semester introductory sequence to better prepare students and to expose them to the content and theory that define an academic major. At many institutions, enrolling in next-level courses and matriculating into an academic major require completion of the introductory course or courses, often with a minimum grade requirement. This gateway reflects not only contemporary enrollment management practices but also traditional pedagogy that learning within an academic major is sequential and that foundational concepts presented in lower level courses should be mastered prior to enrolling in upper-level courses.