Experimental Evidence on the Effect of Full-Day Pre-Kindergarten on Early Elementary Special Education Designations

Abstract

School districts face a difficult decision when considering a move from half- to full-day pre-K, partly because this is a relatively expensive policy option—each half-day classroom/teacher can serve twice as many students (AM/PM) than one full-day classroom. Yet full-day pre-K could confer meaningful benefits to students, by increasing children’s exposure to foundational experiences that support their early development and increasing the time children spend with their pre-K teachers. We explore whether full-day pre-K reduces later special education (SE) designations in ways that could represent a cost-savings to districts, without reducing access to SE services that would have benefited students. Leveraging a randomized field experiment, we estimate the causal effect of full- versus half-day pre-K and find that full-day pre-K leads to a nearly 50% reduction in the likelihood of having an SE designation in early elementary grades among children who, at baseline, exhibit a possibility of benefiting from developmental supports. We also find important differential effects of full- versus half-day pre-K between children whose primary home language is or is not English, as well as male and female children.