For more than 30 years, scholars and practitioners have debated how to distinguish emotional disturbance (ED) from social maladjustment (SM) when determining special education eligibility and need. Scholarship on the nature of ED and SM has paid little attention to the legal parameters of practice despite the fundamentally legalistic nature of special education and resultant special education eligibility determinations. Accordingly, this study systematically reviewed and interpreted the published federal case law distinguishing SM from ED. This analysis of the idiosyncratic constellation of student characteristics and behaviors that courts held were relevant for proving SM or ED sheds light on the types of data school psychologists and multidisciplinary evaluation teams should consider during ED evaluations. The implications for practice and policy are discussed.