Although the theory of the market is well understood, little is known about how for-profit schools will operate in practice. This paper considers why for-profit schooling has developed during the current period and not before (e.g., entrepreneurs must compete against heavily subsidized public schools, which limits their ability to charge prices that fully cover their costs). It also discusses the main input differences between for-profit and public schooling, explaining that the main areas where public, for-profit, and nonprofit schools differ are in their personnel practices, professional development, and managerial practices rather than in their instructional practices. Finally, it examines how for-profit schools will have to attract students as clients. If states and districts insist on using state standards and tests to judge school performance, for-profit schools will not be able to differentiate themselves with claims of superior student achievement. It suggests that given current evidence, the scope for efficiency gains appears limited. Research has not identified substantial economies of scale in education, and for-profit schools may have to devote more resources to marketing their provision rather than to the provision of education. (SM)