Utilizing two studies, this research focused on perceived mastery and dispositional optimism as the main internal resources affecting the subjective well-being (SWB) of young people, as well as on adolescent-parent similarities and the impact of adolescent-parent relationships on adolescents’ internal resources and well-being. The first study investigates the patterns of associations between mastery, optimism, and SWB in everyday life as assessed by positive and negative affect. The second study assessed mastery, optimism, and SWB among adolescents aged 15-19 and, in addition, included an evaluation of parents’ mastery, optimism, and SWB. Study two replicated the results of study one and confirmed the hypothesis that positive associations between SWB indicators and the adolescents’ internal resources of mastery and optimism were shown. The second hypothesis was partially confirmed through the implication that SWB and internal resources may be affected by differential processes. The third and final hypothesis was confirmed and showed significant associations between the adolescents’ relationships with their parents and adolescents’ SWB measures. The two studies confirmed that perceived mastery and dispositional optimism are related to the happiness and well-being of adolescents and young people. The study indicates that the more positive aspects of their lives, namely, internal resources and well-being, also merit investigation and can contribute to a better understanding of the significant developmental processes in adolescence. Tables and references