SUMMARYAims– The present study is part of a longitudinal project aimed at identifying the personal characteristics and the developmental pathways conducive to successful adaptation from childhood to adulthood. The study examined the concurrent and longitudinal impact of self-efficacy beliefs on subjective well-being in adolescence, namely positive thinking and happiness. Positive thinking has been operationalized as the latent dimension underlying life satisfaction, self-esteem and optimism. Happiness has been operationalized as the difference between positive and negative affects, as they are experienced in a variety of daily situations.Methods– In a group of 664 Italian adolescents, a structural model positing adolescents' emotional and interpersonal self-efficacy beliefs as proximal and distal determinants of positive thinking and happiness has been tested.Results– Findings attest to the impact of affective and interpersonal-social self-efficacy beliefs on positive thinking and happiness both concurrently and longitudinally.Conclusions– Adolescents' self-efficacy beliefs to manage positive and negative emotions and interpersonal relationships contribute to promote positive expectations about the future, to mantain a high self-concept, to perceive a sense of satisfaction for the life and to experience more positive emotions.Declaration of Interest: none.