First graders (N = 323) participated in an evidence-based classwide reading program (Peer-Assisted Learning Strategies; PALS). A dual-discrepancy approach was used to identify 56 children whose reading performance and growth rates were substantially below those of average readers, indicating they were not responding sufficiently to PALS. This approach reliably distinguished among unresponsive at-risk, responsive at-risk, and average-performing readers. Nonresponders were assigned randomly to one of three increasingly individualized treatments: PALS, Modified PALS, or tutoring by an adult. No statistically significant between-group differences on reading-related measures were found. Effect sizes (between .30 and .50) comparing groups and proportions of nonresponders following treatment suggest that tutoring was most promising for reducing unresponsiveness.