Purpose: Much justification for third sector involvement in education advances from the notion that attributes from business and non-profit fields could benefit state-run public schools. The purpose of this paper is to explore this issue by examining theoretical underpinnings and expectations for third sector participation in public education systems, particularly with respect to educational innovations and improvements, and the structural opportunities, incentives, and impediments for such innovation. Design/methodology/approach: The question is how third sector participation shapes the rate, nature, and types of innovations in education as schools interact in response to competitive pressures. This conceptual analysis of the third sector examines the political-economic features and structures of the sector in fostering innovation, with reference to the US sector that was specifically positioned to enhance the innovative capacity of publicly funded education. Findings: The analysis indicates that educational innovations are not necessarily more prevalent in or because of the third sector, and that there are obstacles to their creation and diffusion. Moreover, schools often respond to competitive incentives in ways unanticipated by policymakers, such as school marketing rather than instructional improvement, sometimes in ways detrimental to goals set out for public education, such as social sorting. In fact, instead of the third sector simply developing or incentivizing innovations, there is evidence that this sector has adopted innovations developed in the state sector. Originality/value: The analysis suggests that a third sector based more on a professional, as opposed to a competitive, model may better facilitate the development of innovative capacity in education.