Until recently, the determination of whether a child should be considered learning disabled, has involved one basic “test” and multiple exclusionary criteria. The test was whether there was a substantial discrepancy between the child’s achievement and intellectual ability, both measured by standardized tests. Exclusionary criteria included perceptual challenges such as uncorrected vision or hearing dif culties and psychological and social circumstances. It addition, students were not to be considered for learning disability designation unless they had had an adequate opportunity to learn. Among many problems that have been identi ed in the traditional de nition of LD (see Fletcher, Denton, & Francis, 2005; Gresham, 2002; Vellutino, Scanlon, & Lyon, 2000), perhaps the most critical, was the limited attention to the role of instruction in the evolution of learning dif culties. As the legislation provided no clear criteria for determining whether a child’s instruction had been adequate, “adequate instruction” took on many different meanings and often simply meant that the child had attended school regularly. In light of the widely recognized variability in teacher effectiveness and the differences in service delivery models across educational settings (e.g., some schools routinely offered remedial reading services to struggling rst graders while others delayed support services until second or third grade), there were growing concerns that many children were being identi ed as learning disabled because of inadequacies in their instructional experiences. An article by Clay (1987) was perhaps the rst clear articulation of the notion that children should not even be considered for learning disability designation until high quality and responsive instruction had been provided and failed to accelerate the child’s progress. Since Clay’s article, a number of studies have instituted instructional interventions that were successful in preventing and/or remediating early reading dif culties thereby con rming that intensi cation of instruction can reduce the incidence of reading dif culties (e.g., Brown, Denton, Kelly, Outhred, & McNaught, 1999; Center, Wheldall, Freeman, Outhred,

& McNaught, 1995; Mathes et al., 2005; Gomez-Bellenge, Rogers, & Fullerton, 2003; O’Connor, 2000; Scanlon, Vellutino, Small, Fanuele, & Sweeney, 2005; Scanlon, Gelzheiser, Vellutino, Schatschneider, & Sweeney, 2008; Torgesen et al., 2001; Vaughn, Linan-Thompson, & Hickman, 2003; Vellutino et al., 1996). Further, several studies speci cally evaluated the relationships between students’ response to instruction and the size of the discrepancy between their measured IQ and achievement levels (Fletcher et al., 1994; Stanovich & Siegel, 1994; Vellutino, Scanlon, & Lyon, 2000) and found little relationship.