This study investigated the role of early literacy and behavioral skills in predicting the improvement of children who have experienced reading difficulties in 1st grade. The progress of 146 low-income children whose reading scores in 1st grade were below the 30th percentile was examined to determine (a) how the poorest readers in 1st grade progressed in reading achievement through 4th grade and (b) which emergent literacy and behavioral skills measured in kindergarten predicted differential 4th grade outcomes. Results indicated that the divergence between children who improved and those who did not was established by the end of 2nd grade. Further, individual linguistic skills and behavioral attributes measured in kindergarten contributed substantively to this difference. Implications for intervention timing and educational policy are discussed.