Abstract: This study aimed to analyze and determine the core competency, methods of developing core competency and the structure of a program for developing the core competency of public universities supporting-line administrators by examining the core competency that is required for administrators to properly perform their tasks. The research includes a thorough study of 5 components necessary for successful job performance and is applicable to agencies in Thailand or a foreign country. Three mixed methodologies were used in conducting the study: Document syntheses, quantitative research and qualitative research. The results of all 3 methodologies revealed the following: The core competencies necessary for public universities supporting-line administrators in Thailand consisted of 5 aspects in order from the highest to the lowest mean: Teamwork, planning and management, leadership, creative thinking and ethics. With respect to the techniques used to develop these 5 core competencies, 9 techniques in order from the highest to the lowest percentage were apparent: Workshop, training, lecture, supplementary activities, management games, recreational activities, role playing, brainstorming and field trips. For the structure of the program for developing core competency, which was obtained from in-depth interviews with experts by using a structured-interview form, it was found that the experts opined about guidelines, methods, contents of development and methods of assessing all the 5 core competencies. Additionally they felt that a wide variety of different methods should be included in the new program. The experts felt that the contents must cover all competencies by training continuously in the form of 9 learning units for a total of 180 h or approximately 5 weeks of training. In development, there must be an emphasis on leading to real practicability and there must be a variety of methods of assessing development as assessed by superiors, subordinates, work peers and self-assessment both before and after training. Also, there must be assessment criteria.