Using an additional decade of data from the National Longitudinal Survey of Youth 1979 Children and Young Adults (CNLSY), this study replicated and extended Deming’s evaluation of Head Start’s life cycle skill formation impacts in three ways. Extending the measurement interval for Deming’s adulthood outcomes, we found no statistically significant impacts on earnings and mixed evidence of impacts on other adult outcomes. Applying Deming’s sibling comparison framework to more recent birth cohorts born to CNLSY mothers revealed mostly negative Head Start impacts. Combining all cohorts showed generally null impacts on school-age and early adulthood outcomes. (author abstract)