The purpose of this study was to explore the effectiveness of an Orton-Gillingham-based reading instruction system, the Barton Reading and Spelling System (BRSS; Barton 2000), that was used as a supplemental reading instruction program for increasing the lower-level reading skills of a group of adolescents with persistent reading problems. Nine students participated in the supplemental reading program based on pre-test scores of a spoken and written language assessment battery. Progress was measured at the end of intervention by post-testing students on the same assessment battery. Each student showed some improvements from their pretest to posttest scores on all of the measures utilized, with some having moderate to large effect sizes, supporting the view that the BRSS is an appropriate supplemental reading program for struggling adolescent readers within a response to instruction framework. Future research should include a larger sample size and a control group. (Contains 5 tables.)