This paper discusses preservice teachers' use of action research in a Professional Development School setting. Preservice teachers were placed in a PDS site that focuses on internationalizing education and on teaching languages. The teacher candidates were in charge of planning, teaching, and assessing language instruction in their classrooms. The preservice teachers implemented action research. The process helped them adjust to their teaching responsibility. They collected and reflected on their action research data, used it to understand their practice, and then made plans accordingly to improve their practice. This process was empowering and helped preservice teachers grow in their confidence and competence.