Introduction. - A theoretical conceptualization of the relationship between health and happiness and associated factors was studied using a structural equation model. Method. - Data from the Portuguese part of a World Health Organization collaborative study, health behavior in school-aged children [Currie C, Smith R, Boyce W, et al. HBSC, a WHO cross national study: Research protocol for the 2001/2002 survey. Copenhagen: WHO; 2001], were used. A. representative national sample (N = 6131) of 11 -, 13- and 15-year-old pupils was studied [Matos M.G., Equipa do Projecto Aventura Social. A saude dos adolescentes portugueses: Quatro anos depois (La sante des adolescents portugais: quatre ans apres). Lisboa: Edicoes FMH; 2003] and data were analyzed for the purpose of this paper. Results showed a significant positive correlation between perception of health and perception of happiness. A group of personal and social factors was associated with this correlation. Results. - Results demonstrated that personal factors had more impact on health perception, and social factors had more impact on happiness perception. Adjustment fit indexes were good. Socioeconomic status (SES) was significantly associated with a positive health perception, and SES was also significantly but modestly associated with the perception of happiness. Discussion. - Results highlighted the importance of a holistic and positive approach to adolescent health. This study confirmed the importance of family, peer relationship and positive evaluation of the school on adolescents' health and well-being. Results may suggest that preventive interventions in school settings should target both personal factors (e.g., promoting social competence) and social factors (e.g., promoting social support and acceptance). Interventions should also target physical and mental health in order to help adolescents to cope with the daily challenges they meet. (C) L'Encephale, Paris, 2008.