This article reports on a first cycle of a larger action research study conducted to determine how Circuit Teams could support School Management Teams of underperforming high schools towards whole-school development. Although it is a mandated requirement by the Department of Education, none of the four schools involved in the study had developed a school improvement plan, a necessary first step towards whole-school development. In this article we focus on the collaborative intervention we designed to meet the identified needs of the participants regarding the construction of a school improvement plan. A qualitative baseline study revealed the School Management Teams' general disregard towards the school improvement plan as well as limited insight into what skills they needed to develop it, and their imperfect understanding of whole-school development. We explain the action research process we took to facilitate a clearer understanding of the school improvement plan and how to develop it. The data analysis revealed that the collaborative learning experience ignited feelings of empowerment, increased motivation to collaborate with the Circuit Teams towards whole-school development, and generally assisted the School Management Teams' resolve to improve the management of their respective schools. These findings present evidence that suggests the value of an action learning approach to the professional development of School Management Teams, but the process could be equally useful to encourage sustainable change in varied contexts of continued professional development.