This article reports first-year achievement outcomes of a national randomized evaluation of Success for All, a comprehensive reading reform model. Forty-one schools were recruited for the study and were randomly assigned to implement Success for All or control methods. No statistically significant differences between experimental and control groups were found in regard to pretests or demographic characteristics. Hierarchical linear model analyses revealed a statistically significant school-level effect of assignment to Success for All of nearly one quarter of a standard deviation-or more than 2 months of additional learning-on individual Word Attack test scores, but there were no school-level differences on the three other posttest measures assessed. These results are similar to those of earlier matched experiments and correspond with the Success for All program theory. (Contains 6 notes and 6 tables.)