Many college students, especially first-generation and underrepresented racial/ethnic minority students, desire courses and careers that emphasize helping people and society. Can instructors of introductory science, technology, engineering, and math (STEM) courses promote motivation, performance, and equity in STEM fields by emphasizing the prosocial relevance of course material? We developed, implemented, and evaluated a prosocial utility-value intervention (UVI): A course assignment in which students were asked to reflect on the prosocial value of biology or chemistry course content; our focus was on reducing performance gaps between first-generation and continuing generation college students. In Studies 1a and 1b, we piloted two versions of a prosocial UVI in introductory biology (N = 282) and chemistry classes (N = 1,705) to test whether we could encourage students to write about the prosocial value of course content. In Study 2, we tested a version of the UVI that combines personal and prosocial values, relative to a standard UVI, which emphasizes personal values, using a randomized controlled trial in an introductory chemistry course (N = 2,505), and examined effects on performance and motivation in the course. In Study 3, we tested the prosocial UVI against a standard UVI in an introductory biology course (N = 712). Results suggest that the prosocial UVI may be particularly effective in promoting motivation and performance for first-generation college students, especially those who are more confident that they can perform well in the class, reflecting a classic expectancy-value interaction. Mediation analyses suggest that this intervention worked by promoting interest in chemistry.