In the current literature, the role of the head teacher in teachers' professional development has became a foremost concern as compared to the past where head teachers were considered as Fullan says, ;gatekeepers' and administrators of policy. Mostly, professional development was hijacked by external agencies such as educational institutions, donors and other initiators without acknowledging head teachers' role in the initiation. The current literature says that the head teacher plays a key role in teachers' professional development in the school but the question still remains in my mind: is it so in reality? Keeping the question in view, this study was carried out to explore the nature of head teachers' involvement in teachers' professional development. The study was conducted in a government and private system of education in Karachi Pakistan. A qualitative paradigm was followed with a sample of thirteen ADISM (Advance Diploma in School Management) graduate head teachers from the government and the private systems. In this study a small-scale survey for baseline information and follow-up interviews were conducted to collect adequate data. The findings of the study show that almost all the research participants were involved in teachers' professional development in some way. However, there is a difference in their nature of involvement in professional development activities. In the private school the head teachers are providing professional support to the teachers through scheduled [formal] and unscheduled [informal] activities, whereas, in the government system the head teachers are providing professional support to the teachers through informal activities. Further, the study found out some similar issues in both systems The findings show that the head teachers in government system do not have autonomy to go beyond what is stipulated in the policy. They cannot institutionalize any professional development activity without the permission of a higher authority in the system Thus I have recommended for there to be a change in the government policy to empower head teachers to take initiatives to address the needs of the school.