The purpose of this study was to investigate high school teachers' beliefs about inquiry instruction and determine how their beliefs influenced their use of inquiry after a professional development program. Thirty-six high school science teachers participated in this study. The professional development program consisted of a 2-week summer institute as well as academic year support. The summer program included discipline-specific content lessons that utilized inquiry-based instruction, pedagogical practice involving the use of a summer high school enrichment program, and reflection on this practice-teaching in content area groups. Both in-depth qualitative interview and written reflection data were collected as well as data from the teachers' classroom implementation of inquiry. Based on the analysis of the teachers' interviews and classroom enactments, the teachers were placed into four enactment categories: Integrated, Emerging, Laboratory-based, and Activity-focused. We used Windschitl's ("Rev Educ Res" 72(2):131-175, 2002) four constructivist dilemmas as a framework to understand the teachers' enactments. We describe the teachers' beliefs and practices in each enactment category as well as the components of the professional development model that were important to making changes in the teachers' practices. In the conclusion, we connect the enactment levels to the professional development experience and suggest future directions for professional developers to move teachers toward more integrated inquiry practices.