Recent years have seen a shifting landscape around private engagement in K-12 public education, one that involves a reorientation of education policy and practice around the principles of the marketplace. In this article, we examine the roles of both not-for-profit and for-profit agencies, as distinct from government agencies, in this movement. Past research has generally focused on subsets of these private actors (i.e., for-profit firms, charter management organizations, or alternative preparers of educators for public schools). We try to look more broadly in order to examine how private actors and the roles of those players in K-12 education are changing, both in terms of the scope of their engagement and the extent to which their role increasingly involves areas at the core of educational practice. In doing so, we consider some of the reasons for these changes, including the influence of federal policy, markets as drivers, and the broader political context.We conclude by raising questions for future research and examining how these developments intersect with values such as democratic voice, equitable distribution of resources, and the public purposes of schooling.