Children with developmental disabilities are at risk for secondary complications and lower academic performance, which contributes to lower health and well-being and may be ameliorated by access to special education services. This paper examines state variability in preschool special education participation among a United States population-based cohort with parent-reported developmental delays and disabilities. Analyses explore the extent to which observed variability can be explained by state socio-economic attributes and special education policy and funding. Rates of special education varied significantly across states and were highest in states with least income inequality and lowest in states with most income inequality. Place variation in preschool special education participation stems, in part, from child characteristics, but to a larger extent, from state socio-economic attributes.