We find that public preschools are a gateway to health and social services. Low-income children born shortly before their state’s school-entry cutoff date are more likely to receive school-based services, speech-language pathology, occupational or physical therapy, and vision and dental services at ages three and four, compared to children born after the cutoff. They are also more likely to receive financial support through Supplemental Security Income. These findings suggest that preschool enrollment connects low-income children to the health and social service system in ways that extend beyond the classroom.