Abstract
In this article, we considered evidence from our intervention research programs on whether students with learning disability (LD) in reading and mathematics (comorbid LD) respond differently to intervention, compared to students with reading LD alone (RD) or to students with mathematics LD alone (MD). The goal was to gain insight into whether comorbid disorder represents an LD subtype distinct from RD or from MD, which requires differentiated forms of intervention. Our analysis suggested that students with comorbid LD respond differently than those with MD, depending on the nature of mathematics intervention, and may therefore represent a distinctive subtype. By contrast, students with RD appear to respond to intervention in similar ways, regardless of whether they experience RD alone or in combination with MD. Results also suggest that distinctions between comorbid and single-order LD may depend on whether LD is defined in terms of lower- versus higher-order academic skill. Recommendations for future study are provided.