The underrepresentation of Black women in Science, Technology, Engineering, and Mathematics (STEM) is a long-standing issue. According to the National Science Foundation (NSF, 2019), Black women hold less than 10% of STEM degrees, while only 2% work in STEM fields. These disparities can be attributed to structural inequities related to the STEM pipeline. Therefore, to mitigate these disparities, informal STEM education programs can help increase participation in STEM and create more opportunities for Black women and girls. Thus, this collective case study addressed the following research questions: 1. How do adolescent Black girls engage in and respond to informal STEM education programs? 2. How can informal STEM education programs develop adolescent Black girls' STEM identity and increase participation in STEM? 3. What pedagogical practices effectively engage adolescent Black girls in STEM? Purposeful criterion sampling was used to recruit participants for this study. The research process included interviewing four adolescent Black girls who attended informal STEM education programs. To understand each program's process and climate, participants described their experiences through initial questionnaires, interviews, and written prompt responses. Furthermore, this research used critical race feminism and Black feminist thought to analyze five prominent themes from the data. The findings suggest that Black girls who participate in informal STEM education programs (a) benefited from an affirming environment, (b) experienced engaging instructional strategies, (c) utilized support systems, (d) recognized racial representation was significant, and (e) experienced racial microaggressions. In addition, the findings support equitable STEM access for Black girls through informal education programs. The implications of this study also suggest a need to attend to the psychological and emotional needs of Black girls in informal STEM spaces.