This study applies an adapted Tripartite Integration Model of Social Influences (TIMSI) framework to investigate the socialization experiences of undergraduate students participating in the STEM Scholars Program (SSP), with a particular focus on the relationship between first-generation status and STEM socialization. A sample of N = 193 students was longitudinally tracked and surveyed on five occasions throughout their four-year college journey, ranging from the summer bridge to the end of their four academic college years. Through the application of latent growth curve modeling, we identified quadratic growth trajectories in three indicators of social influence/socialization processes (i.e., scientific self-efficacy, scientific identity, and SSP program values), as well as a co-development between social influence processes and scientific integration. Notably, the study finds that first-generation students report comparable growth rates of socialization experiences to their continuing-generation peers. These results suggest that the SSP may help bridge the gap for first-generation students as they embark on their journey into STEM fields. The implications of this study highlight the importance of socialization in STEM education, as well as the recruitment of first-generation students in STEM intervention programs.