Educational action research was carried out between 2003 and 2006, focusing on developing high-school teachers' professional autonomy belonging to the scientific area in poor communes of the ninth Region de la Araucana, Chile. The research is contextualized in the Chilean educational reality and based on each of the stages of the action research cycles--planning, action, observation, and reflection. The educational processes towards developing teacher's autonomy that took place during the three years of the project are described here. Some results obtained in the reflection stages are presented, discussed and interpreted from the information coming from documented tests, participant observation, and deep interviews. Finally, the conclusions drawn from the research findings are presented. (Contains 3 tables and 1 figure.)