This study evaluated the effectiveness of intensive instruction in reading decoding skills with 9th graders at risk for school failure or with learning disabilities. Sixty-two students were identified as reading more one or more grade levels below ninth grade in each of two high schools. Subjects in one school were removed from their English classes for 4 to 8 weeks, during which they received intensive small-group instruction in the Word Identification Strategy, a learning strategy for decoding multisyllabic words. Students in the comparison school received traditional reading instruction in their English classes. Results of posttests revealed that students with learning disabilities in the experimental school (n=11) had gained an average of 3.9 grade levels in reading decoding skills. Matched students in the comparison school had made an average gain of 0.4 of a grade level. The whole group of experimental students had made an average gain of 3.4 grade levels in reading decoding skills compared with an average gain of 0.2 in the comparison school. Results indicate that intense strategy instruction within a relatively short period of time can boost students' decoding skills by several grade levels. (Contains 10 references, 3 figures, and 3 tables.) (Author/DB)