








that is, they are guaranteed seats. We use this fact to construct instrumental variables estimates of the effects of passive charter attendance: the grandfathering instrument compares students at schools designated for takeover with students who appear similar at baseline and who were attending similar schools not yet closed, while adjusting for possible violations of the exclusion restriction in such comparisons. Estimates for a large sample of takeover schools in the New Orleans Recovery School District show substantial gains from takeover enrollment. In Boston, where we can compare grandfathering and lottery estimates for a middle school, grandfathered students see achievement gains at least as large as the gains for students assigned seats in lotteries. Larger reading gains for grandfathering compliers are explained by a worse non-charter fallback.
