Compares the influence of text difficulty on the growth of poor readers' reading ability over 18 weeks of 1-to-1 tutoring. Significant differences favored tutored children. Between approaches, the only significant difference was oral reading fluency, which favored students who read material at their reading level. Students who began with lower fluency made stronger gains in text matched to reading level. (Contains 87 references and 2 tables.) (GCP)