The purpose of the present study was to examine whether significant relationships were found between subjective well-being and social interactions, and also whether a revised program through a writing method adopting a cognitive approach could increase the quality of social interactions and subjective well-being in adolescents. In the first study, we examined the relations between social interactions and subjective well-being. Social interactions were tested by the Rochester Interaction Record (RIR). The quality of social interactions implied closeness, enjoyment, responsiveness, influence, and confidence. The quantity of social interactions implied the number of other people with whom a subject related in a day. In the second study, we produced a revised program into which a program, through a writing method adopting a cognitive approach,(Nedate & Tagami, 1994) was modified. We examined the effects of the program on the quality and the quantity of social interactions and subjective well-being. Results indicated that the quality of social interactions related to subjective well-being and the revised program increased the quality of social interactions and subjective well-being and decreased the quantity of social interactions.