Research Findings: This study reports outcomes from a randomized, controlled trial of an emergent literacy intervention for prekindergarten children at-risk for reading failure. Children (N = 2219) in 114 preschools and childcare centers were screened for eligibility in fall. Children who scored at-risk (n = 476) were randomized to fall or spring treatment and received nine weeks of explicit, multisensory, emergent literacy instruction in small groups provided by early literacy interventionists. Trained observers noted high implementation fidelity. Pre-reading skills were assessed before and after intervention for both treatment groups. The spring intervention group served as at-risk controls for children who completed fall intervention. Three-level, linear growth models (time-student-school) were used to estimate treatment effects, found for print awareness, elision, rhyming, and the screener (print and letter knowledge, phonological awareness), replicating previous findings for the screener, rhyming, and print knowledge, and extending them to elision. Significantly accelerated growth in print knowledge, elision, rhyming, and the screener was observed during intervention. Practice or Policy: Results demonstrate benefits of high-quality emergent literacy instruction for children at risk. Growth in skills for both fall and spring treatment groups following this 18-lesson program supports some implementation flexibility among interventionists with delivery constraints during the year.