This NBER report concludes that teachers whose students tend to show high gains on their test scores (called “high value-added teachers”) also contribute to later student success in young adulthood, as indicated by outcomes such as college attendance and future earnings. To support this claim, it is not sufficient for researchers to show an observed association between teacher value-added and later outcomes in young adulthood. It is also necessary to rule out plausible alternative explanations — for example, that parents who did the most to promote their offspring’s long-term success also endeavored to secure high value-added teachers for their children. This review explains that, for the most part, the evidence needed to rule out these alternatives is missing from the report. Thus, policymakers should tread cautiously in their reaction: the case has not been proved.