What do principals discuss when they get together to "talk shop?" This paper offers some answers and discusses implications for the preparation and professional development of school leaders. The activities reported in the paper were undertaken as part of the Cognitive Approaches to School Leadership (CASL) Project. In the broadest terms the project seeks to apply a set of related theories about how people think about and think through problems to the study of school administration. Data came from observation of a 13-session discussion group composed of 7 principals and from transcription of their conversations. The findings support previous research showing that informal conversations among principals were primarily concerned with the internal aspects of school and school-system operations. One-half of the discussion group's topics of conversation dealt with concrete aspects of school functioning; however, the other half of the topics dealt with more abstract subjects, such as relationship and philosophical issues. The data indicate that principals need secure and open arenas to foster broader professional discussion. Four tables and one figure are included. (Contains 47 references.) (LMI)