We conducted a systematic review of studies that examined the effect of interventions combining a child development component with a nutrition one; in some cases the nutrition interventions also included health-promotion components. Only papers with both child development and nutrition outcomes and rated as moderate-to-good quality were included. Eleven efficacy and two nonrandomized trials, and eight program evaluations were identified. Only six trials examined interventions separately and combined. The trials showed nutritional interventions usually benefited nutritional status and sometimes benefited child development. Stimulation consistently benefited child development. There was no significant loss of any effect when interventions were combined, but there was little evidence of synergistic interaction between nutrition and stimulation on child development. Only three trials followed up the children after intervention. All at-scale program evaluations were combined interventions. Five benefited child development, but one did not, and two showed deficits. There was generally little benefit of at-scale programs to nutritional status. We found no rigorous evaluations of adding stimulation to health and nutrition services at scale and there is an urgent need for them. There is also a need to establish quality-control mechanisms for existing scaled-up programs and to determine their long-term effects. There is also a need to determine if there are any sustained benefits for the children after programs finish.