This study investigated the effectiveness of combining enhanced classroom instruction and intense supplemental intervention for struggling readers in first grade. Further, it compared two supplemental interventions derived from distinct theoretical orientations, examining them in terms of effects on academic outcomes and whether children's characteristics were differentially related to an instructional intervention. One intervention (Proactive Reading) was aligned with behavioral theory and was derived from the model of Direct Instruction. The other intervention (Responsive Reading) was aligned with a cognitive theory and was derived from a cognitive-apprenticeship model. These interventions were provided to small groups of first-grade students at risk for reading difficulties. Students were assessed on various reading and reading-related measures associated with success in beginning reading. Results indicated that (a) first-grade students who were at risk for reading failure and who received supplemental instruction in the Responsive or Proactive interventions scored higher on measures of reading and reading-related skills than students who received only enhanced classroom instruction, (b) enhanced classroom instruction appeared to promote high levels of reading growth for many children at risk for reading failure, (c) the two interventions were essentially equally effective even though they reflected different theoretical perspectives, and (d) children's characteristics did not differentially predict the effectiveness of an intervention.