Early intervention programmes to deliver educational, social, and health services are widely recognised as a potentially effective way of promoting better health and preventing the development of costly health problems. While existing evidence demonstrates the potential benefits of targeted and often intensive interventions, we find that a fully universal, area-based intervention to bring together education, employment, and health services in England has benefits for childhood obesity and hospitalisations. We find that the introduction of Sure Start reduced the probability of being overweight at age 5 by one percentage point (10% of baseline), with stronger effects for white boys. Sure Start also reduced hospitalisations for respiratory illness and infections, consistent with predictions that exposure to additional pathogens would strengthen children's immune systems.