In this study, a school district adopted Kindergarten Peer-Assisted Learning Strategies (K-PALS), a scientifically based, class-wide peer-tutoring program for reading. Sixteen new K-PALS teachers were assigned randomly to receive ongoing support from a university expert or from experienced K-PALS teachers within the district. K-PALS teachers who received university support implemented K-PALS with somewhat higher ("d" = 0.41), but not reliably different, fidelity compared to those who received district support. K-PALS teachers' student reading outcomes did not differ significantly based on whether they received university or district support. However, K-PALS teachers' students reliably outperformed historical controls on beginning reading measures ("d" = 0.24 to 1.29). Implications for further research and for schools' adoption of K-PALS are discussed. (Contains 6 tables, 2 figures, and 1 note.)