Diverse perspectives in science promote innovation and creativity, and represent the needs of a diverse populace. However, many science fields lack gender diversity. Although fewer women than men pursue careers in physical science, technology, engineering, and mathematics (pSTEM), more women than men pursue careers in behavioral science. The current work measured the relationship between first-year college students' stereotypes about science professions and course completion in science fields over the next 3 years. pSTEM careers were more associated with self-direction and self-promotion (i.e., agency) than with working with and for the betterment of others (i.e., communion). On the flip side, behavioral science careers were associated with communion to a greater degree than with agency. Women completed a lower proportion of pSTEM courses than did men, but this gender disparity disappeared when women perceived high opportunity for communion in pSTEM. Men pursued behavioral science courses to a lesser degree than did women; this disparity did not exist when men perceived ample opportunity for agency in behavioral science. These results suggest highlighting the communal nature of pSTEM and the agentic nature of behavioral science in pre-college settings may promote greater gender diversity across science fields.