In order to create long-term academic success for their students, it is critical for classroom teachers and administrators in language immersion settings to be effectively trained in best practices for teaching a second language. The purpose of this outcomes-based program evaluation was to explore the perceived effectiveness of the professional development training offered to teachers at a language immersion school. Constructivism served as the conceptual framework. In this study, the current training models used for elementary school teachers in a one-way language immersion setting were evaluated. Eleven teachers and administrators were interviewed as participants in different language programs. The results were analyzed using inductive analysis by breaking down the data into parts, or frames of analysis, in order to create categories of relationships that would structure the final analysis of themes found in the data. Through this research, certain themes emerged related to the main research question of perceived effectiveness of professional development training. The themes focused on: organizational support, collaborative culture, and perceiving teachers as leaders, coaches, and educators. These findings culminated into a project where the findings were summarized in the form of white paper and presented to the school board and the academic director. The implications for social change resulting from this study are that professional development programs are effective when teachers are entrusted to be leaders, to know where they need to improve, and to support each other in learning and applying learning into the classroom. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]