Purpose: The New Zealand Ministry of Education has constructed a wide-ranging "Professional Development Plan" providing a four-stage national pathway for progression to principalship; the first stage has been the conduction of the National Aspiring Principals Pilot (NAPP) programme in five regional locations. The purpose of this paper is to outline the evaluation of the programme. Design/methodology/approach: A mixed method approach for evaluation was employed where qualitative and quantitative data were collected almost simultaneously, and compared and contrasted. Findings: Key findings indicated overall sound programme delivery, curriculum coherence, high relevancy to stakeholders and good rates of principal appointments. Greater emphasis is placed on distinctive findings that have not been reported elsewhere. These included: primary-sector participants rating course facilitation, online learning, and "relevancy of the course for principal development" more positively than their secondary counterparts; aspirants who had partial or full completion of a relevant post-graduate leadership qualification rating eight aspects of NAPP lower than those without such qualifications; and aspirants who were approached and encouraged to apply for NAPP by their principal and subsequently supported by them, finding the programme more relevant and applicable. Research limitations/implications: The multiple positive outcomes reported reveal short-term programme adequacy and effectiveness against a range of indicators. Long-term impact (including capacity to change leadership practice, student learning and school improvement) evaluation is required to determine sustained effectiveness. Originality/value: The paper provides distinctive findings that have not been reported previously for principal development and more general findings that should inform such development programmes. (Contains 7 tables and 1 figure.)