As colleges and universities aim for greater diversity in their undergraduate populations, one population researchers consider is first‐generation students, or students whose parents do not have a college education. The research reported here addresses first‐generation college students' discipline of study (e.g., biology) and its impact on their persistence. Exploring how female, low‐income, first‐generation college students evaluate their persistence within undergraduate science learning environments contributes to understanding how gender and social class influence persistence in STEM fields. Two White, female, low‐income, first‐generation college students were interviewed during their last year in college. Using constant comparative coding methods and Ricoeur's (Ricoeur [1984] Time and narrative, Volume I (K. McLaughlin & D. Pellauer, Trans.). Chicago, IL: The University of Chicago Press) description of narrative construction, common tensions were identified related to participants' descriptions of undergraduate science as competitive. These persistence‐related tensions are (1) differing experiences in lecture and lab, (2) managing time to work, study, and maintain family relationships, and (3) weighing their personal (family) priorities against the longer time it would take them to reach their science‐related career goals. These tensions depict a traditional undergraduate science learning environment focused on individuals and abstract knowledge that positions female lower‐income students as “academic non‐competitors” because of the importance of kinship ties and physical skills in their cultural background (Lareau [2002] American Sociological Review 67(5), 747–776; Lareau [2003] Unequal childhoods: Class, race, and family life. Berkeley: University of California Press). The participants' experiences support that the gendered and classed expectations needed to succeed in a science environment could be somewhat alleviated through reforms to traditional lecture and laboratory undergraduate science courses that promote cooperative student learning groups and integration of lecture with hands‐on activities. © 2013 Wiley Periodicals, Inc. J Res Sci Teach 50: 802–825, 2013