Success for All (SfA) is a comprehensive school reform program designed to support schools serving many students of disadvantaged backgrounds to increase students' achievement. SfA includes daily 90-min reading lessons with extensive use of cooperative learning, tutoring for struggling readers, and an emphasis on parental involvement. School teams receive coaching and training, and each school has a facilitator appointed who supports program implementation. SfA has shown positive results in the US, and has been translated to the Dutch context. Effects on students' reading achievement were evaluated with a total sample size of 1,011 students from three cohorts. We found a significant positive effect on reading fluency of first-grade students (Cohen's d = +0.40). The effect for the subgroup of low-socioeconomic-status students was even somewhat higher (Cohen's d = +0.63). We did not find significant effects in Grade 2 and Grade 3. We also found no effects of SfA on reading comprehension.