,This study aimed at helping students to improve their leadership skills by utilizing the methodology of Participatory Action Research in which two cycles of research (one cycle per semester) were conducted during the Academic Year of 2021. The three anticipated developmental outcomes of change, learning, and knowledge were gained through the practices, which were administered in the particular setting of the Noensangawittaya School in Chaiyaphum Province. The target group for development consisted of 191 high school students, and 13 teachers served as the study’s co-investigators. The findings revealed the changes that had been anticipated. In accordance with the comparative analysis of the three phases (before and after the first cycle of practices and after the second cycle), it was discovered that in order to improve the students' leadership skills, the co-researchers had continued to increase their activities since beginning the first phase. In a similar vein, there had been advancements in the leadership skills of the students. Together, the research team, the co-researchers, and the school discovered that any form of development, which prioritizes democratic or participatory principles, will produce better results. Additionally, a grounded theory known as the "Model for Developing Students' Leadership Skills: The Success of Lessons Learned through Participatory Action Research at Noensangawittaya School" was developed from the practices, which had been employed in this research.