The focus of this study was to explore if the evaluation process of differentiated supervision contributed to the development of tenured teachers toward teacher leadership in two central Illinois high schools. A theoretical framework, the Teacher Leader Development model, was created based on Dr. Keith Leithwood's development of professional expertise framework, which describes the stages of a teacher's professional growth.

The two central Illinois high schools selected had been utilizing the differentiated supervision process for a minimum of 3 years to evaluate tenured faculty. Participants in the study included teachers from two academic departments, the school administration, and a central office administrator at each school. Participants answered questions that were aligned with the three stages of the teacher leader development model: developing instructional expertise, influencing departmental instructional practices, and influencing school wide instructional practices. Documents that were pertinent to the study, such as school improvement plans, teacher professional growth plans, and district evaluation plans, were analyzed.

The results from the study concluded that while each school utilized the differentiated supervision process to engage faculty in school improvement activities, teacher leadership development was not the focus and thus few teacher leaders emerged. Three teachers who had been involved with leading school wide instructional development activities emerged from the study. For the development of teacher leaders to increase specific support would be needed; a clearly defined vision for teaching and learning, time within the school day for collaboration around solving instructional issues, and networks created to provide ongoing feedback to teachers as they implement new strategies.