The purpose of this varied replication study was to evaluate the effects of a supplemental reading intervention on the beginning reading performance of kindergarten students in a different geographical location and in a different instructional context from the initial randomized trial. A second purpose was to investigate whether students who received the intervention across both the initial and replication studies demonstrated similar learning outcomes. Kindergarten students (n = 162) identified as at risk of reading difficulty from 48 classrooms were assigned randomly at the classroom level either to a commercial program (i.e., Early Reading Intervention; Pearson/Scott Foresman, 2004) that included explicit/systematic instruction (experimental group) or school-designed typical practice intervention (comparison group). Both interventions were taught by classroom teachers for 30 min per day in small groups for approximately 100 sessions. Multilevel hierarchical linear analyses revealed no statistically significant differences between conditions on any measure. Combined analyses that included students from both the initial and replication studies suggested that differences in the impact of the intervention across studies were largely explained by mean differences in the comparison group students' response to school-designed intervention. (Contains 10 tables, 1 figure, and 1 footnote.)