Team-based leadership is increasingly recognized as valid for raising workplace quality. Developing effective teams of leaders, though, is barely understood, scantly researched and not simple or straightforward. Mentoring has been recognized as valuable within teams and with the support of critical reflection can assist in augmenting team-based leadership. This paper presents findings from an action research project in an early childhood center that was nested within a larger practitioner research project. Using action research, practitioner researchers investigated the conceptual interrelationships between team-based leadership, team-based mentoring, and critical reflection. Sociocultural theory underpinned the interactive and collaborative project. A framework for mentoring and critical reflection was developed and implemented to support critical mentoring for team-based leadership. Findings indicated that complex and abstract concepts can be combined to strengthen team-based leadership through mentoring and critical reflection. We argue this was made possible through action research. Our purpose in disseminating this research is to give glimpses into complex and iterative action research processes; to show that clarifying and integrating key concepts enabled the full potential and impact of the work to be realized; and to contribute to the knowledge by showing that action research is a powerful approach for addressing quality issues.