Abstract The research aimed to develop a participatory internal supervision approach for the development of participatory supervision in small-sized schools under the Khon Kaen Office of Primary Educational Service Area 1. Using the method of research and development methodology, divided into 4 phases: phase 1: draft internal guidelines on participatory internal supervision approach, phase 2: develop a participatory internal supervision approach, phase 3: check for suitability by implementing, and phase 4: conclusions and reflections on participatory internal supervision approaches. The research sample consisted of (1) teachers who work in small-sized schools under the Khon Kaen Office of Primary Educational Service Area 1. The tools used in research was questionnaire to find current situation and problems of Internal supervision (2) the purposive group were teachers at Baan Sa Ngam school at this area, and the tools used by data collection to attitudinal evaluation form. Statistics data analysis were mean, percentage, and standard deviation. The research results: The guidelines of development for participatory internal supervision approach for small-sized schools under the Khon Kaen Office of Primary Educational Service Area 1, There were 3 components as follows: The component 1: internal supervision and there were 4 principles: (1) empowerment (2) human resources development (3) participation (4) quality development. For the component 2: the internal supervision process was as follows: (1) planning for supervision; (2) give knowledge to understanding the work; (3) operation (4) encouragement and (5) performance appraisal. The 3 component was the efficiency of internal supervision as follows: (1) development results to achieve for both knowledge, ability and attitudes towards classroom research models. (2) the satisfaction of teachers with the participatory internal supervision approach.