This was a qualitative research, which explored how the school community experienced the outcomes of leadership on the effectiveness of the school improvement program (SIP) on Sidama Zone schools, Ethiopia. Four schools were purposively selected. Data were collected using interviews, focus group discussions, observation and documents, which included school plans, reports, minutes of meetings, memos, letters and the students' examination results were analyzed as they reflected issues related to the outcomes of the SIP on the school's effectiveness. Principals, teachers, students, supervisors, parent teacher association members and SIP experts were interviewed. The findings indicate that in schools where there is strong collaboration of the school community in the planning, decision-making, monitoring and evaluation processes, the improvement initiatives are owned by all in the school and the performance of the schools is enhanced. It is recommended that the roles of the principals be redirected, the number of supervisors be increased, diverse professional development opportunities for principals and teachers be created, the recruitment, appointment and retention of principals be reconsidered and mechanisms to check school plans and performance reports be created.