This study examined the relationship between meaning in life, optimism and well-being among adolescents. A total of 1807 adolescents in Hong Kong completed inventories that assessed their personality, psychosocial problems and life satisfaction. Results of structural equation modeling (SEM) indicated that both meaning in life and optimism significantly associated with multidimensional life satisfaction and multidimensional structure of psychosocial problems among adolescents. Optimism also served as a partial mediator in the relationships between meaning in life and both positive and negative aspects of well-being. The mediating role of optimism did not differ across gender.