This article is aimed at describing Collective activity strategyof CPD to improve teacher at Islamic High School of Pesantren. Using qualitative approach in the form of a naturalistic phenomenology, the research setting was three Islamic high school of Pesantren. Data collection techniques used was in-depth interviews, observation, and documentation. Data analysis uses the main steps of data condensation, data display, and verification/drawing conclusions. The result shows that the preparation of teachers for relevant CPD, building self-awareness of teachers toward self-improvement of knowledge and skill, and the use of various of collective activities of CPD. Besides, the school principal also builds self-awareness of teachers by motivating, supporting, and facilitating teachers to carry out self-development on personal initiative (self-initiative) outside the school program