Much has been written about the controversy surrounding performance-based school closures, but there has been no rigorous assessment of their impact on student achievement. Does the closure process harm students who are enrolled in a school while it is being phased out? Are future students better-off because a low-performing option has been eliminated? To explore these questions, the authors studied the 29 high school closures begun between 2003 and 2009 in New York City to determine the degree to which a closure affected a range of student outcomes, including graduation rates, mobility, attendance, and academic performance. They analyzed outcomes for 20,600 affected students: 9th-grade students who chose to stay after a closure announcement, 9th graders who transferred elsewhere, and rising 9th graders required to attend different high schools because of a closure. They found that for students already enrolled in a school that was later closed, the phase-out process did not have a systematic impact, positive or negative, on precise mechanisms that explain closures' impact or lack thereof. More research is needed to understand how school closures affect factors like teacher performance, student and staff morale, and family engagement over time. Their findings, however, suggest that high school closures in New York City during this particular period produced meaningful benefits for future students while not harming, at least academically, the students most immediately affected by them.