The chance of a secondary education for young girls who might have otherwise been among many out-of-school youth cultivates aspirations for their future. While aspirations to be educated expand the possibilities of opportunities, they also go unfulfilled in an environment of low achievement rates, high unemployment and constraining gender norms that can leave many secondary graduates disempowered. This study examines how aspirations, agency and future well-being are linked through 4 years of longitudinal data from interviews with girls in a technical and vocational school in rural Tanzania. Conceptually, the paper puts forward a framework within a capability approach to consider how aspirations and agency are oriented toward valued well-being. It also draws inspiration from Appadurai's use of aspirations as a cultural concept that is future and change oriented and socially embedded. Finally, the body of scholarship that frames Bourdieu's notion of agency as productive is drawn upon to illuminate whether and how girls are agentic in acting toward their aspirations. Bringing these conceptualizations together, the empirical analysis shows how aspirations and agency are dialectically related and socially situated, allowing for openings in agency to occur even when faced with gendered constraints to aspirations.