Outcomes for students classified as emotionally disturbed (ED) are among the poorest for any disability group and include disturbingly low graduation rates, poor academic achievement, high rates of school suspensions and school dropouts, and chronic interpersonal problems. Additionally, these students are often underserved within the school setting with an overall prevalence rate of less than one percent. This underservice may be partially due to the definition of ED provided in the Individuals with Disabilities Education Improvement Act (IDEA, 2004), which is vague, contradictory, and redundant. Additionally, IDEA does not provide guidelines for how to assess for ED, thus, assessment procedures and prevalence rates widely differ by state. We propose the use of a Response to Intervention (RTI) model for the assessment and treatment of students with ED. Within an RTI model, students are provided evidence-based interventions implemented with integrity, and their response to these interventions is continuously monitored. This article defines RTI and describes methods of screening, assessment, treatment, and outcome evaluation for ED within the model.