Balanced literacy has been proposed as a compromise or middle ground between philosophical approaches to reading instruction that stress teaching of word recognition and those that stress construction of meaning. The purpose of this study was to evaluate the effectiveness of the READ 180 balanced literacy supplementary instruction program on improving reading performance of underachieving students in a predominantly Hispanic urban high school. Students predicting failure on the high school graduation test were assigned to the READ 180 program during the first semester of Grade 10. Comparison of language arts scores on the New Jersey Assessment of Skills and Knowledge in Grade 8 with language arts scores on the High School Proficiency Assessment in Grade 11 showed that both English learners (EL) and English proficient (EP) students in the balanced literacy supplementary program improved from predicting below the cutoff for high school graduation to scoring above the cutoff. However, whereas EP's in the balanced literacy intervention still scored below their EP peers not in the supplementary program, EL's in the balanced literacy program scored above their EL peers not in the program. Results suggest the benefit of a balanced literacy supplementary instruction program for underperforming English learners at the high school level.