In order to corroborate and grow teacher educator knowledge (TEK) scholarship, this paper describes an in-depth-focused exploration of a group of teacher educators providing professional development. Our grounded data analysis allowed us to define different major elements, sub-elements, and components that comprise TEK, as well as make explicit how the use of this knowledge--in the context of teaching professional development--draws upon multiple components at any given moment. These findings hold implications for TEK scholarship and practice. Specific to scholarly efforts, while current models for TEK are useful for explicating common understandings amongst the research community, the most functional representations should be fluid and dynamic, in part by balancing both breadth and depth in their scope. Specific to the development of teacher educators, teacher educator preparation should recognize, emphasize, and develop future teacher educators' layered understandings (i.e. knowledge of students and teachers) and robust knowledge of contexts.