["Journal of Research in Science Teaching, EarlyView. ", "\nABSTRACT\nScience identity is a key predictor of persistence in STEM. Although prior research has established the importance of social recognition for identity development, less is known about how recognition operates within informal, everyday interactions. This explanatory sequential mixed methods study investigated whether and how social recognition during informal science talk contributes to science identity and STEM persistence, particularly for undergraduate women who often encounter gendered barriers within scientific environments. The quantitative strand included a longitudinal survey of 211 undergraduate STEM majors. Results showed that social recognition during conversations about science predicted increases in science identity and indirectly predicted STEM persistence through increases in science identity, but only for women. The qualitative strand consisted of semi‐structured interviews with 22 undergraduate women in STEM and elaborated the mechanisms underlying these relationships. Women described recognition as occurring through specific conversational behaviors, including attentive listening, follow‐up questions, remembered interests, encouragement, and being treated as knowledgeable by others. These interactions helped women reappraise doubts about their competence, validate their legitimacy as “science people,” and strengthen motivation to persist in STEM pathways. Interview data also revealed that recognition was shaped by relational context and social comparison. Recognition from professors often signaled legitimacy within scientific spaces, recognition from family members often communicated encouragement and support for students' interests and aspirations, and recognition from peers often shaped students' visibility and sense of belonging within science‐oriented social groups. Women further described how racialized and gendered microaggressions undermined recognition and required them to repeatedly prove their competence, particularly for Black and Latina participants. Together, the findings suggest that informal social recognition functions as a relational mechanism through which women develop science identities and sustain persistence in STEM. Fostering recognition in everyday interactions and educational contexts may therefore represent an important pathway for advancing equity in STEM.\n"]