Our peer-led collaborative learning groups, called Workshops, have now had extended success in two upper-level courses in chemistry and biochemistry. These Workshops are in turn supported by a third upper-level course for training peer-leaders. Our data confirm that the initial positive results from the introduction of Workshops in organic chemistry and in biochemistry have been maintained over time and over changes in course instructor. In addition, training upper-level Workshop leaders has contributed substantially to the self-sustaining character of our program. These longitudinal results have been accompanied by the lateral spread of Workshops into other courses and departments. The concurrent development of mutually reinforcing partnerships among faculty, staff and students has supported these changes. Complementary adjustments in institutional practice, and the recent establishment here of a Center for Workshop Education now provide a formal framework to foster the continuing promise of our Workshop program. (Contains 3 tables and 2 figures.)