A significant minority of jurisdictions in the United States offer extreme emotional disturbance (EED) as a partial defense to murder. The form of this defense, as established by statute and case law, varies widely among jurisdictions. Empirical research on EED is scant with little guidance to forensic mental health professionals on how to approach and conceptualize potential EED cases. This paper addresses these issues by being the first known published work to (1) set forth a contemporary map of the varying definitions and scope of EED across the United States, (2) translate legal terminology into constructs accessible to forensic evaluators, and (3) provide legal and clinical analyses of sample EED cases to highlight key differences in the form of the defense and the admissibility of evidence between jurisdictions.