Over the last several decades, research has examined how students' beliefs about school and about their own abilities affect their academic goals, motivation, and achievement (for reviews see, Dweck, Walton, & Cohen, 2011; Farrington et al., 2012). It has also investigated how these beliefs and associated patterns of behavior can be influenced through interaction with others (Gunderson et al., 2013; Linnenbrink, 2005; Mueller & Dweck, 1998; Turner et al., 2002) and through precise, psychological interventions (J. Aronson, Fried, & Good, 2002; Blackwell, Trzesniewski, & Dweck, 2007; Cohen, Garcia, Apfel, & Master, 2006; Good, Aronson, & Inzlicht, 2003; Walton & Cohen, 2007, 2011; Wilson & Linville, 1982, 1985; Yeager & Walton, 2011). This research has focused on the educational context, but it has provided rich, generalizable insights. It has revealed a complex cross-section of the ways in which individuals' worries and motivations interact with their social environments to affect their behavior and major life outcomes. The education context is in many ways ideal for the study of psychology. There are unambiguous, regularly-collected, socially meaningful outcomes; there are complex, but consistently structured relationships; and there is diversity, yet commonality, in people's aspirations and concerns. The schoolhouse has always been a rich source of data for psychologists (Berliner, 2006; Davidson & Benjamin, 1987). However, as computers increasingly saturate education, the schoolhouse and its contemporary equivalents provide unprecedented opportunities for psychological researchers: Opportunities to make a measurable and socially meaningful impact on the lives of students and teachers; opportunities to display to society at large the benefits of a careful, psychologically-wise approach to solving social problems; and opportunities to learn about psychological theory by pushing its predictions to the limit in new contexts and at new scales of operation. This dissertation investigates these opportunities from several different perspectives. Chapter 1 focuses on education as a context for psychological research: I elaborate on the factors that make education a rich context for psychological research, and I describe how researchers have used this context to apply and to further basic psychological theory. In Chapter 2, I focus on the the benefits, challenges, and methods of large-scale research. Chapters 3-5 each present data from a different, large-scale efficacy study. Chapter 3 presents a study of the robustness and generalizability of two social psychological interventions across a sample of over 1500 students from 13 socio- demographically heterogeneous schools. Chapter 4 describes the process of selecting and customizing psychological interventions to address psychological obstacles to success in community college math. Chapter 5 tests the efficacy of psychologically wise encouragement in a sample of over 250,000 online learners. In Chapter 6, I explore how the local context influences students' responses to a growth mindset intervention and the relationship between individual students' mindsets and achievement. Finally, Chapter 7 reviews what we have learned about psychology through recent large-scale studies in education; it considers what new areas deserve exploration; it provides loose estimates for the economic impacts of psychological interventions in schools; and it discusses psychological interventions as a vehicle for large-scale social change.