This chapter reviews research and practice pertaining to mathematics interventions from historic and critical lenses. We refer to mathematics interventions as programs that are layered on top of core mathematics instruction time, based upon a gradual-release model of instruction, and implemented with learners with math difficulties and disabilities. We summarize the research on supplemental instruction, suggest conditions under which a re-conceptualization of supplemental intervention research and practice may be warranted, present a case of one student for which the effectiveness of traditional methods stands in question, and provide practical implications for teacher practice in supplemental intervention settings.