Improving education and labor market outcomes for low-income students is critical for advancing socioeconomic mobility in the United States. We explore how Massachusetts public high schools affect the longer-term outcomes of low-income students, using detailed longitudinal data. We estimate school value-added impacts on four-year college graduation and earnings. Similar students who attend schools at the 80th percentile of the distribution are 6 percentage points more likely to graduate from a four-year college and earn 13% (or $3,600) more annually at age 30 compared to peers who attend schools at the 20th percentile. We consider how school effectiveness across a range of short-term measures relates to longer-run impacts. Schools that improve students' test scores and college aspirations improve longer-run outcomes more.