One of the most important questions in education research is whether the gains from interventions for which perceived short-term success can be sustained. The possibility of short-lived impacts is especially relevant for research on charter schools, where charter operators who face high-stakes assessments have an incentive to "teach to the test." The fact that charters are subject to intense scrutiny and evaluation may even create incentives for cheating (Jacob and Levitt, 2003), strategic instruction (Jacob, 2007), and a focus on small groups of students that are pivotal for official accountability measures (Neal and Schanzenbach, 2010). The purpose of this paper is to assess the impact of attendance at Boston's charter high schools on outcomes where the link with human capital and future earnings seems likely to be sustained and strong. Specifically, the authors focus on outcomes that are either essential to or facilitate post-secondary schooling: high school graduation, the attainment of state competency thresholds, scholarship qualification, Advanced Placement (AP) and SAT scores, college enrollment, and college persistence. Importantly, most of these outcomes are less subject to strategic manipulation than are the state's test-based assessments. As in earlier work, the research design implemented here exploits randomized enrollment lotteries at oversubscribed charter schools. The resulting estimates are likely to provide reliable measures of average causal effects for charter applicants. Six tables are appended.