STEM education is an approach to teaching and learning that integrates the content and skills of science, technology, engineering, and mathematics; which promotes critical thinking, higher-order thinking, and problem solving (NSTA, 2020). This research was conducted with the purpose of identifying the influence of this PD on improving teacher librarians’ knowledge, skills, and abilities to support STEM education efforts in their schools. This study utilized a pre/post-test quasi- experimental design to determine the influence of the PD on teacher librarians’ knowledge, skills, and abilities to support STEM education (Creswell, 2013). The pre-test data confirms previous research, that there is a significant gap in the knowledge, skills, and abilities of school librarians when it comes to supporting STEM education efforts in their schools. Additionally, school librarians aren’t being offered many professional growth opportunities to further their knowledge in this area. Post-test data provides information on the influence that the PD had on the participants' knowledge, skills, and perceived abilities in supporting STEM education.