Inquiry-based instruction and instruction about nature of science (NOS) are central to reform-based science teaching. Professional development (PD) is a well-recognized way to support teachers in learning about and using new pedagogical approaches. At present there is a lack of information regarding what teachers learn during inquiry PD programs, if this learning impacts their teaching, and evidence linking teacher learning to student learning. To begin addressing these issues, first, I conducted a critical review of the literature on teacher PD. I analyzed 17 PD programs supporting teachers in learning about inquiry to determine the extent to which they aligned with features of effective PD outlined in the literature. I then critiqued the outcomes of the studies based on the methods employed by the researchers. Findings suggested a general alignment with recommended features of effective PD with a few notable exceptions, including: supporting teachers in developing inquiry-based lesson plans, providing authentic inquiry experiences, and focusing on science content for teachers. The review also revealed that no study connected participation in inquiry PD with all the desired outcomes of teacher PD: enhanced teacher knowledge, change in beliefs and practice, and enhanced student achievement. Second, I examined the teaching practice and views of inquiry and NOS of a group of highly-motivated teachers before their participation in an inquiry PD program. Findings indicated most teachers held limited views of inquiry-based instruction and NOS. Moreover, most teachers used primarily teacher-centered instructional practices and elements of inquiry were observed in less than half of the classrooms. The study provided empirical evidence for the claim that even some of the best teachers struggle to enact reformed-based teaching. Further, it highlighted the critical need for an agreed upon definition of inquiry-based instruction and rigorous PD to support teachers in learning about reform-based teaching. Third, I examined science content knowledge and views of inquiry and NOS of a group of 5th9th grade teachers before and after participating in an inquiry PD. Analysis of pre and post-program instruments indicated project teachers showed greater gains in subject matter knowledge than comparison teachers and the relative change was significantly different statistically. Additionally, most project teachers demonstrated a shift from less informed to more informed views of inquiry and NOS. Finally, analyses of postprogram questionnaires and interviews indicated that supporting teachers in reflecting on the relationship between their classroom teaching practice, and new knowledge acquired during PD, may be an important link in enhancing teacher knowledge to changing practice. A future study will follow several participant teachers into their classrooms after the PD in order to understand how the PD experience impacted their teaching.