This study examined the effects of teaching through traditional versus learning-styles instructional methods on a sample of 323 heterogeneously grouped adolescent and adult learners’ achievement, retention, attitudes, overall assessment and understanding of the advantages of learning Swedish grammar. In a counterbalanced design, the control group was taught about grammar with a traditional teaching method and the experimental group was taught the same content with Multisensory Instructional Packages (MIP) (Dunn & Dunn, 1992). Statistical analyses included analysis of variance with two independent variables (learning-style versus traditional methods) and three between-subjects variables (sequence, age, and learning-style type). Discriminant analysis and F-tests were used. The research design was quantitative, but incorporated qualitative components of triangulation. Significantly more positive differences (p ≤ 0.01) were revealed in achievement, attitudes, retention, overall assessment and understanding of the advantages of grammar when students were taught with learning-styles responsive instructional strategies as opposed to when they were taught traditionally. The findings indicated that learning-styles methodology provided a practical, positive means of individualizing instruction and simultaneously improving learners’ attitudes toward learning grammar.