This research investigated the impact of a professional development program on enhancing fifth-grade environmental science teacher efficacy through place-based education (PBE) practices--the Meaningful Watershed Educational Experiences (MWEE) Professional Development Training aimed to promote teacher engagement and increase pedagogical content knowledge. The study utilized a mixed-methods approach, incorporating qualitative and quantitative data collection methods. Results showed significant improvements in teacher efficacy, with participants demonstrating an increased perception of being able to lead lessons in the schoolyard effectively. Results varied based on previous experience in using PBE. More experienced teachers demonstrated less growth, while new and less experienced teachers had more significant growth based on survey results. Teachers reported an increased desire to incorporate more content standards with PBE. This study's findings have important implications for environmental science training geared toward elementary science teachers, fostering, and promoting environmental literacy through the use of the schoolyard. Overall, this research contributes to the field of environmental science education and provides insights for effective professional development strategies to enhance teacher efficacy and student learning outcomes. [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.]