Physical inactivity and mental health issues are considered central risk factors for developing non-communicable diseases. A large part of the population in insufficiently active and mental health issues are increasing. To counteract the unfortunate prevalence of these phenomena, it has been suggested to target determinants of physical activity and well-being, such as physical literacy. Physical literacy is such a determinant. Physical literacy describes the individual's foundational for participation in physical activities and is often defined as "the motivation, confidence, physical competence, knowledge and understanding to value and take responsibility for engagement in physical activities for life" (International Physical Literacy Association). It is, grounded in theory, hypothesized to be important for well-being in physical activity contexts, and therefore also for all well-being. In this thesis, four direct and indirect hypothesized associations between physical literacy, physical activity and well-being are outlined by unfolding the theory of physical literacy and self-determination theory and reviewing the literature. The aim of this thesis was to investigate the four hypothesized associations empirically by conducting three individual cross-sectional studies, synthesizing results across the three studies and combining the results with previous evidence and theoretical perspectives from physical literacy and self-determination theory.