Instructional design scholars have emphasized the development of theories and models more than the study of professional practice. Although both theoretical and practical knowledge are essential in a professional discipline, the field has not yet articulated the relationship between the two types of knowledge and how understanding this relationship can lead to improved professional practice. In this article, the authors describe the roles of theoretical and practical knowledge in the field, offer a framework for examining the foundational assumptions and personal beliefs associated with these types of knowledge, and suggest a way for designers and theorists alike to engage in forms of reasoning that lead to the development of a conscience of craft. They continue by arguing that the more one develops a conscience of craft, the more effective and alive one's practice becomes. The article concludes with implications for educational programs that prepare instructional designers. (Contains 1 figure and 1 table.)