The selection of the right leadership style by the principal will be able to bring the school towards improving quality and service. This study aims to describe and analyze the principal's leadership style in an effort to improve the performance of teachers and education personnel and to explore the factors that influence the principal's leadership style at SMA Negeri 2 Lumajang, East Java, Indonesia. This study uses a descriptive qualitative approach with a case study research design, the data collection techniques used are non-participant open observation, semi-structured interviews and documentation studies, techniques for data validity using credibility, transferability, dependability and conformability. The results showed that in leading the principal using a group leadership style. The influencing factors consist of a leader who has personality, past experience, high expectations for all school personnel to develop the school, puts forward the process of carrying out tasks, subordinates show enthusiasm and willingness to change, provide direction on task clarity, organizational climate and policies able to help improve the quality of human resources in the school environment.