Abstract
This research aims to determine the strategies for developing teacher professionalism by school principals at SMKN 2 Kuripan. The research approach used is qualitative with a case study method. Interview, observation, and document review methods are used to collect data. Data analysis is done through data collection, condensation, presentation, and conclusions drawing. Checking the validity of the data is carried out using credibility, transferability, dependability, and confirmability tests. The research results show that: 1. The coaching strategy carried out by the head of SMKN 2 Kuripan School uses formal and non-formal strategies; 2. The effectiveness of the coaching carried out by the principal can be seen from the teacher's discipline, the teacher's presence in teaching in class, the teacher's performance through PKG, the active role of the teacher in participating in activities that support the development of teacher potential; 3. The impact of coaching carried out by the school principal has a significant influence because of the encouragement of facilities and motivation that the school principal always provides; it influences teacher performance and achievement; 4. School principals and teachers face obstacles in carrying out professional development. Some teachers are not disciplined in attending routine training, some experience a decline in performance, as seen from PKG, and some continue to use outdated teaching methods without updating their approaches to current developments.