<p>Social and emotional learning positively impacts children’s and adolescents’ well-being and happiness, both short- and long-term. However, little is known about the impact of these competences on self-perceived well-being in family and school. The present study examines the links between social and emotional learning, school and family well-being, and subjective happiness, the mediational power of school and family well-being in the relationship between social and emotional learning and subjective happiness, and the present study assess the effects of sociodemographic variables on family and school well-being and subjective happiness. Three hundred and forty-one children and adolescents between 7 and 18 years old, assessed their social and emotional learning (self-awareness, self-regulation, interpersonal relationships, social awareness, and responsible decision-making), subjective well-being related to school and family contexts, and subjective happiness. The results showed that social and emotional competencies were positively associated with perceived school and family well-being as well as subjective happiness. In the mediation analysis, only self-awareness and relationship skills positively impacted on subjective happiness via family and school well-being. This study demonstrates the promising relevance of social and emotional learning to well-being in the contexts children and adolescents are in, and their overall happiness, and reinforces the importance of family and school in fostering happiness.</p>