Response to Intervention (RtI) is a multitiered system of support, designed to improve student learning outcomes and early identification of struggling students. Much attention has been paid to RtI for literacy at the elementary level, but less on RtI for mathematics at the secondary level. The current case study examines one high school's implementation of an RtI program in mathematics. The main results included the inconsistent rate of growth across students in the RtI mathematics classes and the lack of a statistically significant relationship between tier status and rate of improvement; the inconsistent implementation of a general theorized RtI for mathematics model; and the perceived greatest benefit by students of the Tier 2 math class appeared to be the two certified mathematics teachers.