This review considers both the content and methodologies of 5 single-subject and 2 group experimental design studies investigating the effects of cognitive strategy instruction on the mathematical problem solving of students with disabilities, using quality indicators proposed by Horner et al. (2005) and Gersten et al. (2005). Findings indicated that the research base of both single-subject and group experimental studies did not meet the methodological criteria to support cognitive strategy instruction as a evidence-based practice for improving mathematical problem solving of students with disabilities. The shortcomings identified in the empirical literature supporting cognitive strategy instruction, however, can be addressed in future intervention studies bearing in mind the quality indicators and standards for determining evidence-based practices. (Contains 3 tables.)