A shortage of highly qualified math and science teachers pervades the U.S. public school system. Clearly, recruitment of talented STEM educators is critical. Previous literature offers many suggestions for how STEM teacher recruitment programs and participant selection should occur. This study investigates how early STEM majors who are not already considering teaching careers experienced a summer teaching recruitment internship and how it influenced their ideas about teaching and learning and interest in teaching high school as a possible future career. Using multiple qualitative data sources including interviews and daily internship reflections, a multi-case comparative case study was developed. The findings support that some interns substantially increased their interest in teaching careers, while other interns' interest did not change or decreased. The impact of the recruitment internship was related to extent to which interns (1) found teaching rewarding, (2) focused on student learning rather than behavior, and (3) developed close connections with students and appreciated their individuality. Implications for future recruitment efforts and research on teacher recruitment are provided.