The goal congruity perspective provides a theoretical framework to understand how motivational processes influence and are influenced by social roles. In particular, we invoke this framework to understand communal goal processes as proximal motivators of decisions to engage in science, technology, engineering, and mathematics (STEM). STEM fields are not perceived as affording communal opportunities to work with or help others, and understanding these perceived goal affordances can inform knowledge about differences between (a) STEM and other career pathways and (b) women’s and men’s choices. We review the patterning of gender disparities in STEM that leads to a focus on communal goal congruity (Part I), provide evidence for the foundational logic of the perspective (Part II), and explore the implications for research and policy (Part III). Understanding and transmitting the opportunities for communal goal pursuit within STEM can reap widespread benefits for broadening and deepening participation.