Since its founding 34 years ago, Teach For America has prepared nearly 70,000 recent college graduates and career-changers to teach in high-poverty schools across the United States. Unlike traditional teacher-preparation programs, it places "corps members" in short-staffed public schools after an intensive summer seminar, before they are fully certified to teach, and provides additional support and training during a two-year stint in the classroom. The program, which is part of Americorps and known broadly as TFA, has been both successful and controversial. To fully understand the impact of TFA on student learning, the author states a need to assess the performance of these alumni over the longer term. The New York City Department of Education, the nation's largest school district, has hired nearly 6,000 TFA corps members since 1990. The author's analysis is based on New York City public schools that hired both TFA and non-TFA teachers between 2012-13 and 2018-19. TFA and other alternative-certification programs have grown rapidly over the past three decades. While these teachers have higher rates of turnover after they are hired, they also are dramatically more racially diverse than teachers trained in traditional college-based programs. TFA, though a smaller provider, has influenced the national conversation about who should teach American students and how best to prepare those recruits.