In the United States and elsewhere in the world, disabilities are being studied by two different schools of thought: special education and disability studies. In the field of special education, analyses are often pragmatic and instrumental. In contrast, analyses in the field of disability studies are often historical and cultural, explaining disabilities as constructed by social value. This lack of agreement about disabilities leads us to ask: How can practitioners and researchers begin to address the issue of which students might need intensive interventions for their disabilities through the response to intervention (RTI) approach when disabilities are viewed so differently by scholars in the field? In this article I compare and contrast the philosophical foundations of disabilities in special education and disability studies and conclude that the dimensions of pragmatic, instrumental, historical, and cultural factors must be taken into account in order to achieve both the macro and micro levels of RTI implementation.