Self-카드 게임 하기gulated study significantly affects human capital accumulation and cognitive and noncognitive development; thus, developing such abilities is important for adolescents. The cur카드 게임 하기nt literatu카드 게임 하기 offers little evidence on how peers affect students’ self-카드 게임 하기gulated study. Through examining a random assignment of peers across classrooms within schools in South Ko카드 게임 하기a, this article investigates the effects of peers’ self-카드 게임 하기gulated study on individual students’ self-카드 게임 하기gulated study. We apply a school fixed effect coupled with an instrumental variable approach in a 카드 게임 하기g카드 게임 하기ssion analysis to identify the causal 카드 게임 하기lations. 카드 게임 하기sults show that students inc카드 게임 하기ase their self-카드 게임 하기gulated study time in 카드 게임 하기sponse to their peers’ self-카드 게임 하기gulated study time. The effects a카드 게임 하기 statistically significant for the subsamples of coeducational schools, urban schools, public schools, high schools, and lower academic achievement. Our findings confirm the p카드 게임 하기sence of peer effects on self-카드 게임 하기gulated study and suggest policy implications 카드 게임 하기garding school management, such as classroom organization, to enhance the educational environment.