This study examined the impact of Oregon Reading First on student reading outcomes. Outcomes in schools that began Reading First implementation in 2003-2004 (Cohort A) were compared to outcomes in schools that began Reading First implementation in 2005-2006 (Cohort B). The primary hypothesis, that experienced Cohort A schools would outperform less-experienced Cohort B schools, is linked to the model of Reading First used in Oregon and evidence that school reform outcomes can improve over time with high-quality reforms and strong implementation. School-level analyses involved 51 schools and over 3,000 K-3 students. In the major analysis year, 2005-2006, Cohort A schools consistently outperformed Cohort B schools on both formative and summative measures. Also, Cohort A schools had consistently higher rates of within-year reading growth on formative measures. Findings are discussed in the context of the national Reading First Impact Study. (Contains 2 figures, 5 tables, and 2 notes.)