According to research findings, most students who experience foreign language learning problems are thought to have overt or subtle native language learning difficulties, primarily with phonological processing. A recent study by the authors showed that when a multisensory structured language approach to teaching Spanish was used with a group of at-risk high school students, the group's pre- and posttest scores on native language phonological processing, verbal memory and vocabulary, and foreign language aptitude measures significantly improved. In this replication and follow-up study, the authors compared pre- and posttest scores of a second group of students (Cohort 2) who received MSL instruction in Spanish on native language and foreign language aptitude measures. They also followed students from the first study (Cohort 1) over a second year of foreign language instruction. Findings showed that the second cohort made significant gains on three native language phonological measures and a test of foreign language aptitude. Follow-up testing on the first cohort showed that the group maintained its initial gains on all native language and foreign language aptitude measures. Implications for the authors' Linguistic Coding Deficit Hypothesis are discussed and linked with current reading research, in particular the concepts of the assumption of specificity and modularity.