Organizational maturity can inform decision-making, build strategy and underpin development. This paper argues that 'Governance Maturity Theory' (GMT) can act as a developmental modality for school Governing Bodies - and offers an alternative to disciplinary mechanisms such as inspections. Evidence generated by governors, Chairs, and Governance Professionals of Boards in England were used to map the value of inspections for developing school governance and to co-construct GMT. Grounded in organizational maturity theory and governmentality, the project developed two key findings. First, despite inspections driving much of what schools and Boards did, they had diminished the role of governance and had negligible value as either a developmental framework or for ascertaining the value of governors' work. Second, GMT could support Boards to build their decision-making and strategic leadership capabilities and drive their development. The paper concludes that GMT can enable Boards to resist the inspectorate's gaze and its notions of undemocratic 'good' governance and move towards mature strategic leadership.