Professional learning of teachers and instruction have paramount importance if improved student performance is desired. Despite their recognized importance, there is a clear paucity of research on the field of professional development (PD) and instruction. Moreover, the association between professional development and instruction has not been well documented. This study addressed these two gaps by taking a broad perspective in defining professional learning of teachers and providing a theory-based description of effective instruction. Using a large-scale data set, Teaching and Learning International Survey (TALIS) 2013, with 1475 teachers teaching 7, 8, and 9th grades, the interrelationships between the quality of PD experience, school-based professional communities (SBPC), and effective instruction were investigated using single-level structural equation modeling (SEM). This theory-building study showed that PD quality, SBPC, and contextual factors were all statistically significant predictors of teachers' reported use of effective instructional practices. Additionally, with the mediating effect of SBPC, the indirect effect of PD quality was revealed as being statistically significant. The total effect of PD quality was also statistically significant in the structural model. The results translated into the inference that professional learning at the school context should be taken account when teachers' experience in PD activities are concerned in PD research. The effect of PD events was stronger with the spillover effect that SBPC provide. The results of this study provided insight about research on teacher learning, PD effectiveness studies, and professional learning at the school context. The results of this study also created an answer to the call for high-quality educational research by using a large-scale, nationally representative dataset along with advanced statistical analyses to provide methodologically rigorous, empirically-derived evidence of the relationships between professional learning opportunities and effective instruction. Moreover, this study provided data-informed and theory-driven directions for researchers about teachers' professional learning and their instructional practices. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]