In the United States, the long-term effects of early childhood programs have been given particular weight in research on early childhood education and in policy debates about the value of prekindergarten. Many research teams were building the evidence base on U.S. early childhood programs to inform that discussion when studies were upended by the COVID-19 pandemic. In this article, we describe the theoretical and practical risks the COVID-19 pandemic poses for longitudinal studies of preschool intervention programs. We also discuss the potential opportunities the crisis offers by introducing new variation in postprogram experiences for addressing new questions. The article intersects the resilience and disaster literatures with theoretical frameworks for the persistence of preschool effects. We conclude with recommendations for how longitudinal studies of cohorts affected by COVID-19 can enhance our understanding of the mechanisms behind the persistence of preschool effects. (author abstract)