This dissertation examines how 17 school leaders from six at-risk schools in the Golden Triangle of Thailand perceived the development of their leadership qualities through an Action Learning (AL) leadership development program and what factors in the AL program enabled that development. The Golden Triangle is the border area between Thailand, Myanmar, and Laos. This area in Thailand is considered one of the largest human and drug trafficking destinations, sources, and transit countries. The schools here regularly encounter leadership and administrative problems, as well as limited resources, while trying to deliver a quality education to at-risk students. The Ministry of Education, Thailand (MOE) uses the National Institute of Development of Teachers, Faculty Staff, and Educational Personnel to provide professional development programs for pre-service and in-service school administrators. These programs have not proven effective. To provide a more effective development method for leadership behavior, the researcher recommended an AL program to MOE. AL is an approach to working with and developing people through the real work of the school/organization. The recommendation was accepted by MOE, and the researcher co-designed an AL program with AL designers and practitioners and local experts and leaders. The researcher then designed a qualitative case study to determine if participants perceived a change in their leadership behaviors and characteristics and what factors in the AL program may have supported that change. The study employed five research methods: a survey with an expert panel, self-administered surveys, critical incident questionnaire (CIQ) interviews, debriefing sessions with the program coaches, and document analysis. The findings from the study showed the school context had a strong influence on the results. The design of Critical Success Factors in the AL program helped support the development of some leadership qualities and the transfer of that learning back to the schools. Results/conclusions indicated participants perceived some improvement in nine leadership qualities with strongest results in Communication Leadership, Caring Leadership, Collaboration, and Confident Leadership. Recommendations were suggested for AL designers and practitioners, MOE administrators, and future research.