Background: Little is known about the cost-effectiveness of parent training programs when offered universally in U.S. elementary schools in disadvantaged urban communities. Objective: To estimate the cost-effectiveness of a universal school-based implementation study of the Chicago Parent Program (CPP). Methods: CPP was offered universally from 2014 to 2017 to parents of PreK students in 12 Baltimore City Title 1 schools (n = 380; 61.1% Black/African American, 24.1% Hispanic). CPP program implementation and operating costs were estimated using microcosting methods and data drawn from study records. A Complier Average Causal Effects (CACE) framework was used to estimate an Incremental Cost Effectiveness Ratio (ICER) for CPP's average cost per child per 1% decrease in conduct problem prevalence at follow-up. This ICER was then compared with comparable ICERs for four parenting interventions that have been implemented and evaluated in Europe: Connect, Incredible Years, COPE, and Comet. Results: CPP cost $937.51 per child (95% CI: $902.09 to $971.92). Adjusted CACE estimates indicated that CPP resulted in a 31.4% reduction (95% CI: -39.7% to -23.9%) in conduct problem prevalence at follow-up among children whose parents attended CPP. The mean ICER for CPP was $29.86 per each 1% reduction in prevalence (95% CI: $21.05 to $50.71). CPP's ICER was similar to ICERs for Connect ($25.50) and COPE ($29.72), and less than ICERs for Incredible Years ($50.36) and Comet ($59.69). Conclusion: School-based CPP offered universally to parents of children transitioning to Kindergarten in extremely disadvantaged U.S. urban communities was found to offer relatively good value compared with similar parenting programs that are widely used in Europe.