This study examined the effectiveness of an assessment and intervention study targeting prekindergarten children at risk for reading failure. Across 38 child care sites, 220 children were identified as "at risk" for reading failure due to their performance on a screening measure of early literacy skills and randomly assigned to receive immediate or delayed intervention. The intervention consisted of eighteen 30-minute lessons delivered twice weekly for 9 weeks and focused on teaching critical emergent literacy skills within small groups. Hierarchical linear models were used to nest children within center and measure treatment and dosage effects for students' residualized gains in rhyming, alliteration, picture naming, and print and letter knowledge skills. Results indicated significant treatment effects on two of four outcome variables (rhyming and alliteration) and significant dosage effects on all four variables. The study demonstrated a significant positive impact of this intervention for prekindergartners at risk for reading failure. (Contains 5 tables and 1 note.)