This paper reports on a two-year project to form teaching development groups in engineering departments. The goal of each group was to discuss and implement interactive teaching strategies (e.g., in-class problem solving). The research design used meetings notes, feedback from group leaders and a case study of one participant to describe how the groups can be designed to support teaching development. This research was grounded in the following questions: What are the design principles underlying a successful, ongoing, small-group model for faculty teaching development? What logistical and structural features are important for ongoing faculty teaching development in a small-group format? This paper presents the five principles identified in the study and provides a case study of an engineering faculty member's teaching innovations over the several years during and after his participation in the faculty development group.