The purpose of this study was to explore the effects of aligning classroom core reading instruction with the supplementary reading instruction provided to 133 struggling grade 2 readers. A 2-group, pre-posttest true experimental design was employed in this study. In 11 elementary schools, 12 teachers taught both the aligned and unaligned core and supplementary reading treatments. Students in both treatment conditions, aligned and unaligned, made statistically significant reading progress during the 20-week study. Students in the aligned reading instruction treatment group evidenced higher, statistically significant mean residual gain scores on all measures of reading at posttest. Effect sizes, favoring the aligned treatment condition, were small for all reading measures when comparing the 2 treatment groups' mean residual gain scores. This study indicates consistent advantages for aligning supplementary reading instruction with the core reading instruction provided to struggling grade 2 readers. (Contains 4 tables.)