A study investigated the use of horizontal instruction to teach Spanish-speaking secondary students an inferential English reading skill. It looked at (1) the relationship between the students' class-inclusion skills and their ability to identify the implied main idea, (2) the effect of sequentially-developed classification lessons on the students' ability to identify the implied main idea, and (3) the effect of the language of instruction (monolingual or bilingual) on the students' ability to learn a comprehension skill. The results suggest that the students used schemata, including classification in part-whole relationships, during the process of learning English reading skills, implying that the ability to classify is necessary to many learning activities. However, this study does not clarify how such skills should be taught. (MSE)