Questions persist regarding implementation of mental health promotion, prevention, and early intervention initiatives in schools. To date, attention has targeted the "Whats" and "Hows" in design and implementation. Ongoing clarification of "Who" the key proponents are working in this space receives less consideration. This paper presents outcomes from a national colloquium involving leaders from organizations committed to school-based mental health practice in Australia. The aim of the colloquium was to introduce the concept of Intermediary Organizations (IOs) examining this for its potential contribution to improved mental health and school improvement. The central challenge for IOs is implementation, that is, assisting in knowledge mobilization connecting research to policy and practice. The colloquium discussion was grounded in an understanding of public value as an organizing principle for improving public sector effectiveness. The participants evaluated the nature, role, and potential contribution of IOs. Three key issues emerged as being central to effective implementation: health promotion and prevention, relational ethics, and evidence-based practice.