This study aims to: (1) Describe the strategy of Muhammadiyah 2 Surakarta high school principals in improving school quality, (2) Describe teacher performance at Surakarta Muhammadiyah 2 High School in improving school quality. This type of research is qualitative. Research design is case study. Data collection techniques through interviews, observation, documentation. Data analysis techniques with interactive models include data collection, reduction, data presentation, conclusion drawing. The validity of the data is done by data source triangulation and method triangulation.The results of the study show that: (1) the principal's strategy is to make a four-year plan containing short, medium and long-term programs which are then delegated to the vice principal, homeroom teacher, teaching teacher and staff staff (2) Teacher performance in improving school quality through assignments given by the principal. Teachers are also given trainings such as seminars, training and workshops to become competent teachers. Competent teachers can support the improvement of school quality both in academic and non-academic terms
