The purpose of this systematic review was to examine the effectiveness of proportional reasoning interventions for students with learning disabilities (LD) or mathematics difficulty (MD). We evaluated fifth to ninth grade interventions on proportional reasoning content, instructional features, and disability and difficulty identification. The nine studies that met inclusion criteria yielded intervention effects ranging from g = -0.10 to 1.87 and from Tau-U = 0.88 to 1.00. Two of the nine studies were deemed high quality and very few studies included participants with LD. Although most studies identified the concepts addressed in the interventions, authors rarely provided in-depth descriptions of how the concept was taught. The results suggest that proportional reasoning interventions for students with LD and MD is underinvestigated. We posit that intervention research in proportional reasoning can and should be expanded upon and offer suggestions in terms of how researchers can continue to develop the knowledge base.