Two-year, play-based, full-day kindergarten (FDK) has been shown to have long-term academic and self-regulation benefits for young children. This article addresses the question of whether FDK has particular benefits for children who may be at risk for placement in special education. Participants included 592 kindergarten children in their second year of kindergarten, with an average age of 5 years, 9 months. Parent reports indicated that 56% of the children spoke a language other than English at home. The research design exploited a natural experiment that occurred due to the phasing-in of FDK, creating two groups of children who attended either FDK or half-day kindergarten (HDK). Kindergarten children's outcomes in vocabulary, reading, writing, mathematics, and self-regulation were used to create two achievement groups based on data cut-points: below average and average to above average. Following a series of binary logistic regression analyses, results showed that HDK children were significantly more likely than FDK children to be in the below average group in the areas of reading, vocabulary, and self- regulation. In fact, results for self-regulation showed that HDK children were three times more likely to fall into the below average group. These results are consistent with our larger study on the longitudinal impact of FDK to Grade 3. The article discusses the importance of play-based learning in fostering self-regulation and providing opportunities for small-group learning in the FDK program. For children who struggle academically, full-day learning through play with the guidance of an educator team may present additional benefits.