Psychological capital (psycap) pertains to the psychological resources of hope, efficacy, resilience, and optimism. It has received much attention in the industrial-organizational literature and is related to a wide range of adaptive job-related outcomes. However, most of these studies have been conducted on adult populations and the role of psycap in the school context has not been given enough attention. The current study aimed to develop a measure of psycap for the school context and examined how it was associated with academic-related (e.g., motivation, engagement, achievement) and well-being (e.g., life satisfaction, affect) outcomes among school-aged populations. Study 1 (N = 1159) demonstrated that the School Psychological Capital Questionnaire developed in this study had excellent psychometric properties. School psycap positively predicted optimal motivation and engagement. Study 2, a cross-sectional study conducted among high school students (N = 246), revealed that school psycap was associated with optimal academic and well-being outcomes. Theoretical and practical implications are discussed.