The current study adopts a mixed-method research design to foster English Language instructors' attitude toward professional development, self-efficacy beliefs, and reflective thinking. Vygotsky's sociocultural theory constituted the base and the professional development program was designed accordingly. The participants of the study were nine English Language instructors working at three different universities. Throughout the 16-week program, it was aimed to equip the participants with action research skills to conduct their own study in their own context according to their needs and/or interests. All the participants completed the Plan, Act, Observe, and Reflect stages of the Action Research Cycle.