In the last two decades, market design research has influenced how students apply and gain admissions into school in the United States and around the world. This talk will review some basic ideas of economists who focused on resource allocation problems applied to school admissions. We will then review some developments in the field, in the United States and elsewhere. Finally, we will turn to how making it easier to get into school allows us to learn more about what makes a school effective and how this information can ultimately improve the productivity of the education sector.