Identity development in the learning sphere is an important identity-defining issue for Japanese adolescents during the transition from high school to university. The present study reports a preliminary feasibility evaluation of an intervention program designed to facilitate identity formation in the learning sphere. 179 Japanese university freshmen were enrolled in a 5-week intervention program focusing on cooperative learning, aimed at developing their own ideas and styles about learning. Four identity statuses in the learning sphere were formulated, and changes in status during the program were examined. Changes into more developed statuses were more frequent than changes into less developed statuses. The results also showed that students helped each other to develop their identity in five ways. These results suggest the effectiveness of the intervention program. Implications for promoting adolescent identity development are discussed.