Programs for parents of young children hold considerable promise for improving children's life-course trajectories and for reducing health and development problems and associated costs to government and society. To date, this promise has not been achieved. Fulfilling the potential of parenting interventions will require substantial improvements in current practice for developing and testing such programs. Intervention development will be improved if clinicians and investigators ground parenting interventions in theory and epidemiology; and carefully pilot them to ascertain program feasibility, participant engagement, and behavioral change prior to testing them in randomized trials. Studies of parenting interventions will be improved if they adhere to the highest standards for randomization; if they examine objectively measured outcomes with clear public health relevance; and if they minimize selection factors known to compromise the analysis of data. Policy and practice recommendations for parenting interventions will be improved if they are based upon replicated randomized controlled trials, if the interventions are tested with different populations living in different contexts, and if they are examined in dissemination studies before public investments are made in such programs. Procedures need to be developed to ensure that the essential elements of evidence-based parenting programs can be implemented reliably in a variety of practice settings so that they will produce their intended effects. To date, few programs have met these high programmatic and evidentiary standards, with the result that many large-scale policy initiatives for at-risk parents have failed. Evidence is accumulating, however, that some programs delivered by professionals, especially nurse home visiting programs for pregnant women and parents of young children, produce replicable effects on children's health and development, and that these programs can be reliably reproduced with different populations living in a variety of community settings.