This case study examined the opportunities for self-directed learning and the resulting science, technology, engineering, and mathematics (STEM) outcomes among participants in a STEM Girls program. The research questions guiding this analysis are as follows: (a) In what ways does the STEM Girls class provide participants with opportunities for self-directed learning? and (b) What are the STEM knowledge, identities, and attitudes among participants in the STEM Girls class? Findings suggest self-directed learning is addressed by empowering middle school girls to take ownership of STEM experiences through project choice and exploration. Data indicate that STEM knowledge increased and STEM identities were strengthened through greater STEM interest and future STEM engagement (education and career). Future research may include a larger number of participants at various school sites to provide a deeper understanding of self-directed learning and STEM learning experiences on middle school girls' STEM knowledge, identities, and attitudes.