Conceptual model-based problem solving (COMPS) was tested for its efficacy in teaching a student diagnosed with autism spectrum disorder to solve word problems involving multiplication and division. A single-case, multiple-baseline across behaviors design was conducted. The ability to solve each of three types of multiplication problems examined (equal groups, multiplicative comparison and Cartesian product) was addressed separately. The student's performance improved in all three, and it was maintained five weeks after the intervention. The student also generalized the effects of instruction to two-step (addition and multiplication) word problems. Knowledge transfer to an everyday situation was also assessed. The implications of these findings for teaching multiplicative word problems to students diagnosed with autism spectrum disorder are discussed.