Students' achievement-related self-beliefs, as manifest in values, goal orientations, perceived efficacy, mindsets, and a sense of autonomy and self-determination, have been the centerpiece of motivation theories that describe learning and development. The premise of the current special issue is that these intrapersonal beliefs tell us only half the story. We argue that what is missing from much of the current work on motivation is recognition of the rich and nuanced characteristics of students' interpersonal relationships, learning contexts, and cultures and their attendant social processes, all of which can influence an individual student's motivation and engagement. We believe that unless the processes that explain how these influences take place are explicitly acknowledged and studied in greater depth and frequency, the field of motivation will not move forward in meaningful ways. Toward this end, we have invited authors in this special issue to highlight theoretical frameworks and targeted motivation constructs that inform these issues, describe specific social constructs and processes that might explain contextual influences, and propose new directions for motivation science that will integrate these social perspectives with more traditional intrapersonal models of motivation. Their papers focus on a range of social processes emanating from interpersonal contexts most central to children's lives, and they focus on ways in which these processes support (or undermine) students' motivation to learn. Additional topics include discussion of how characteristics of these relationships intersect with and are shaped by the broader social contexts in which they are embedded, such as socially engineered learning structures and culturally based ideologies.