This research is motivated by the importance of the Intra-School Student Organization (OSIS) as a strategic forum for developing the potential of student leadership character, but in practice there are still many unplanned and unsystematic program management. The general objective of this research is to describe and analyze the OSIS management in fostering student leadership character at SMP Negeri 2 Cipeundeuy and SMP Negeri 4 Cipeundeuy, West Bandung Regency while the specific objective is to analyze the process of planning, organizing, implementing, and evaluating, as well as the impact of coaching on student leadership character. The theoretical basis used refers to the POAC (Planning, Organizing, Actuating, Controlling) management function of George R. Terry and the student leadership theory of Kouzes and Posner. This research uses a qualitative approach with a case study method through data collection techniques in the form of observation, documentation studies and in-depth interviews with the principal, vice principal for student affairs, mentors and OSIS administrators. The results of the study indicate that planning is carried out collaboratively with a strong legal basis; organizing is implemented through a clear division of tasks to foster responsibility; The program's implementation prioritizes independence and disciplined coordination; and evaluation is conducted regularly through accountability reports to provide constructive feedback. Through this management, students' leadership character, encompassing integrity, responsibility, empathy, courage, communication, and collaboration, has been comprehensively developed. The study's conclusions confirm that effective OSIS management serves as a "character laboratory" capable of fostering student leadership.