The aim of this study was to explore how counselors of a science, technology, engineering, and mathematics (STEM) focused out-of-school time (OST) program understood ways to support students’ social-emotional learning (SEL) and STEM identity development, as well as the impact on counselors’ awareness of their own SEL and STEM identity. To do this, I developed the STEM-Social Emotional Learning for Facilitators (STEM-SELF) intervention. The STEM-SELF intervention focused on 1) implementing a series of workshops; 2) engaging counselors in a cycle of praxis as they created and implemented experiences for students; and 3) engaging counselors in reflection on the learning gained within the program context and in their own personal context. For the intervention, I used a professional learning community (PLC) to engage counselors in cycles of praxis and designed learning activities based on Knowles’ (1980) principles of adult learning. The content counselors learned focused on STEM identity theory, the SEL framework developed by the Collaborative for Academic, Social, and Emotional Learning (CASEL), and modification of the Ways of Being model. The design was a primarily qualitative action research study and data collection and analysis happened in stages that aligned with the stages of implementation of the STEM-SELF intervention. Data included counselors' reflective journals and one-on-one interviews; the analysis was based on a reflexive thematic analysis approach. The study concluded that counselors gained confidence in facilitating SEL and STEM identity development activities and their understanding of SEL and STEM identity became more refined. Counselors also reflected that their learning was directly applicable to their contexts outside of the OST program. Additionally, counselors' awareness of their own SEL increased, and their conception of what made someone a “STEM person” changed.