To encourage dialogue among professionals, this occasional feature is a forum for the opinions, ideas, and work of a variety of constituents concerned about learning disabilities. For criteria and submission guidelines, please visit www.cldinternational.org and select Publications. The modern history of the legal protections for students with learning disabilities in K-12 education focuses on the Individuals with Disabilities Education Act (IDEA), which is funding legislation with detailed accompanying regulations that, respectively, are periodically revised as part of the reauthorization process. In contrast, Section 504 of the Rehabilitation Act ([section] 504), which dates back to 1973, and its sister statute, the Americans with Disabilities Act (ADA), have played a rather distant secondary role for students with learning disabilities specifically (e.g., Zirkel, 2006) and students with disabilities generally in elementary and secondary education (Zirkel, 2004). The current focus on response to intervention (RTI) exemplifies the seeming primacy of the IDEA in terms of the legal eligibility of students with learning disabilities and, thus, their entitlement to substantive treatment, such as individualized appropriate education, and procedural protections, such as complaint resolution investigations and impartial due process hearings. Yet, the literature in the field has largely failed to recognize the emerging significant impact of [section] 504 that results from the recent Americans with Disabilities Act Amendments (ADAA). This article provides a brief overview of the respective roles of RTI under the IDEA and [section] 504 as a result of the ADAA in terms of the legal eligibility and, thus, entitlement, of students with learning disabilities. RTI UNDER IDEA Thus far, although the literature is replete with promotion of and debate about RTI (e.g., Burns, 2007; Fuchs & Deshler, 2007; Gresham et al. 2005; Kavale, 2005), the legal effect has been relatively slow in taking shape. As explained in more detail elsewhere (e.g., Zirkel, 2008), the most recent reauthorization of the IDEA and its resulting regulations expressly permit but do not require RTI, while changing the status of the severe discrepancy approach from mandatory to either permissible or prohibited, with the ultimate choice left initially to the state level. Thus far, only a handful of states have elected to mandate RTI and prohibit severe discrepancy, with the vast majority instead opting to delegate the choice to the local level (Zirkel & Krohn, 2008). As a result, the case law, which consists of published hearing/review officer and court decisions under the IDEA concerning eligibility for the classification of specific learning disability (SLD), continues to hinge on the severe discrepancy approach. More specifically, the case law prior to the effect of IDEA 2004 reflected a pronounced tendency to uphold district decisions of SLD noneligibility based on either the lack of preponderant proof of (a) severe discrepancy or (b) the need for special education (Zirkel, 2006). The latest case law continues the same trend. For example, there have been 10 subsequent and pertinent published decisions, and RTI was only mentioned in one case, where the hearing officer displayed confusion about it and in any event where its role was of no consequence (High Tech Middle Media Arts School, 2007). All but one of the cases, which had an inconclusive outcome (E.N.v. Pajaro Valley Unified Sch. District, 2008), were in favor of the defendant district based on lack of severe discrepancy and/or the need for special education (e.g., Hood v. Encinitas Union School District, 2007; Jaffess v. Council Rock School District, 2006; M.P.v. Santa Monica-Malibu Unified Sch. District, 2008; S. v. Wissahickon Sch. District, 2008). In the relatively few states that have mandated replacing severe discrepancy with RTI as the approach for determining SLD eligibility under the IDEA, with the understanding that the evaluation must be based on a variety of sources, the litigation is still only in the gestation stage. …