This paper describes the findings that emerged when a New Zealand professional development organisation reviewed its model of delivering assessment for learning in primary and secondary schools. The evaluation was prompted by the need to supplement an annual review of student achievement data and teacher capabilities data with a more systemic review of the programme. The evaluation framework used was informed by a best evidence synthesis produced by Timperley, Wilson, Barrar, & Fung (2007), which identified 10 salient principles for professional development and learning. Using these 10 principles, the professional development model was reviewed, paying particular attention to how each stakeholder group was involved in, and was likely to be affected by, the programme. The conclusion was that whereas there were strong inquiry processes attached to teaching, inquiry was not being fostered at a leadership level. Also, where skills and dispositions related to inquiry were not fostered among leaders, there was a risk that substantial school review was unlikely to be sustained post-contract. This paper has implications for those involved in delivering professional development and for schools that are interested in embedding a culture of professional inquiry.