Professional development (PD) is used as the primary means for ensuring the continued learning of teachers. PD opportunities and support vary in type and quality. Little is known about the participation in and support of PD for high school science teachers. The establishment of supportive professional cultures provides a means to support teachers' PD in addition to providing meaningful interactions between teachers to improve practices related to teaching, learning, and assessment. Even less is known about patterns of relationships between professional culture with high school science teachers and students. PD and professional culture have been reported to increase teacher retention and student achievement. The studies presented in this dissertation use mixed methods approaches to explore data collected by the Policy Research Initiative in Science Education Research Group during the 2007-2008 academic year. The first study assessed PD of high school science teachers from two perspectives: (1) teachers' participation in PD, and (2) schools' practices to support teachers' participation. Teachers' participation was determined using self-reported survey data. Schools' PD support was operationalized using data collected from administrative interviews. Descriptive statistics revealed little relationship between teachers' participation in PD, schools' PD support, and teacher retention. Descriptive statistics of schools' PD support indicated associations with student achievement. The second study operationalized school science professional culture with a rubric developed for the study. Elements within the rubric addressed many components mentioned in the literature as indicative of positive professional culture. School science professional culture had little relationship with either teacher retention or student achievement. Strong associations were found among the elements associated with school science professional culture. These results provide support for the inclusion of these elements in future studies of school science professional culture. The final chapter provides a summary of both studies. Recommendations are made for improving policies in place to support PD and professional cultures experienced by high school science teachers. Specific attention should be directed at the development of cohesive PD programs that address both schools' and teachers' needs. Additionally, more opportunities for in-depth communication regarding school practices for teaching, learning, and assessment need to be provided.