This study investigated the impact of a graduate course that focused on picture books on teachers' understandings of the picture book format and the ways in which these understandings influenced their self-reports of picture book use in the classroom. Findings of this qualitative investigation revealed that immersion in and analysis of the picture book format resulted in important changes in teachers' understandings of and literary stance toward picture books. In addition, teachers reported changes in their instructional practices which, in turn, led to reported changes in their students' construction of meaning as they interacted with picture books.