Following the initiation of educational reforms, this article reports on the different models of leadership that have emerged as being important for developing teacher professionalism in government primary schools in Karachi, Pakistan. The evidence from the case studies, reported in this article, illustrates that even within formalized government primary school structures, such as those in Pakistan, principals can make a shift from traditional leadership styles to more contemporary approaches designed to enhance teacher professionalism. The first section of the article presents the literature review and the background analysis. In the second part, information about the research project and the development of the four cases is provided. The third section utilizes the findings from the four case studies to discuss the central roles played by the school principals in enhancing teacher professionalism and the key leadership models that have emerged as important as a result of performing these roles. Finally, the article argues that the principals require training for high quality leadership in similar types of schools in Karachi. (Contains 1 figure and 1 note.)