The identification of students with learning disabilities (LD) has increased more than 200% since the category was established in 1977 (see for reviews, MacMillan, Gresham, Lopez, & Bocian, 1996; MacMillan & Speece, 1999). There are many competing explanations for the growth in identification of students with LD, ranging from those suggesting that it is an expected outcome from a maturing field (Hallahan, 1992) to an explanation that LD is a sociological sponge mopping up the spills of general education (Lyon, 1999). Despite the many possible explanations for the increased identification of students with LD, there is little doubt that the growth rate of identifying LD is high, the heterogeneity of individuals identified as LD is great, and that many students are either misidentified or unidentified (Epps, Ysseldyke, & McGue, 1984; Reschly, Tilly, & Grimes, 1999; Vellutino, Scanlon, & Lyon, 2000). Discrepancy between IQ and achievement as a means of identifying students with LD has been at the heart of the controversy over identification. The use of discrepancy as a means for identifying students with LD is perceived by many as unfounded and central to the challenge of appropriately identifying and serving students with LD (see for review, Fletcher et al., 1998; Fletcher et al., 2001; Siegel, 1999; Vellutino et al., 2000). The many flaws identified in the discrepancy between IQ and achievement criteria include: (a) IQ is not an indicator of potential, (b) the psychometric properties of the standardized tests often prevent students from receiving the special help they need until they are age 9 or older, (c) discrepancy scores are unreliable, (d) the focus on students' academic needs is not prioritized, (e) discrepancy is not a valid marker for disability, and (f) misidentification rates are high, including overidentification of students without LD, misidentification of students with other disabilities, and underidentification of students with genuine LD that go unnoticed. How to identify and provide services for students with LD is an issue that has been hotly debated within special education since 1977 when the Federal government identified LD as a category of special education and mandated services for these students.
