Understanding how to engage history teachers in effective professional development, rooted in pedagogical content knowledge (PCK), is critical with the implementation of the Common Core State Standards. In this study, we utilized Grant and Gradwell's (2010) notion of ambitious teachers, which built upon Shulman's (1986) concept of PCK, to understand the instructional decision-making of secondary U.S. history teachers participating in professional development through a Teaching American History (TAH) grant. We used a sequential mixed methods study design, which included 3 critical case studies of teachers and a cluster analysis of survey findings from 51 teachers. We described teachers' classroom practices related to historical content and skills, in relation to teachers' involvement in professional development and their schooling contexts. The findings of this study provide examples of ambitious U.S. history teachers who provided student-centered instruction that engaged students in the discipline of history. For contexts similar to this study, an implication of the study findings might be to incorporate approaches in professional development that are rooted in PCK and that help teachers understand their students.