First-generation college students (FGCSs) are a growing population in undergraduate education. Research on FGCS primarily focuses on the challenges and barriers they encounter in college. While important, this literature offers a limited view of FGCS as learners. Moreover, minimal literature has examined these students' lived experiences within sciences, technology, engineering, and mathematics (STEM). This study explores the learning experiences of FGCS (N = 17) in undergraduate STEM programs at a mid-sized, private, predominantly white institution. Guided by the frameworks of intersectionality and social cognitive career theory, the researchers utilized a qualitative, phenomenological research methodology to hear the perspectives of FGCS to and to identify problematic higher educational structures in STEM. Findings point to an elitist stance underlying STEM programs based in general disciplinary norms that restricted FGCS access to STEM majors and careers across social, academic, and professional elements of the academic experience. FGCS who were multiply minoritized based upon race, gender, and social class experienced the compounding of marginalization, and academic success and persistence came at a personal cost. Students also reported relying predominantly on personal strengths and motivations to overcome elitism in STEM rather than on institutional supports. Findings also highlight the variation in the first-generation experience and identify the unique barriers FGCS encounter within STEM fields. Implications for dismantling inequitable structures for higher education in STEM attending to the social, academic, and professional inclusion of FGCS.