This secondary data analysis of the High School Longitudinal Study of 2009 (HSLS) examined math efficacy among 9th-grade students with disabilities (n = 2,065), as well as the instructional efficacy among the mathematics teachers to whom they were assigned (n = 1,478). Follow-up tests showed both positive and negative relationships between each of the measures and certain educational conditions that HSLS addressed. Implications for policy and practice are provided, as are limitations and future research suggestions.