It is widely thought that many psychological disorders involve emotion dysregulation. However, it is not yet clear just how many of the disorders presented in the Diagnostic and Statistical Manual of Mental Disorders-IV-Text Revision (DSM-IV-TR) are formally characterized by emotion regulation difficulties and related affective disturbances. To address this issue, we first define emotion, emotion regulation, emotion dysregulation, and affective disturbance. Next, we systematically code the psychological disorders listed in the DSM-IV-TR in terms of the presence or absence of affective disturbance and emotion dysregulation. We then use an emotion regulation perspective to examine affective disturbances in Axis II disorders, with a focus on borderline personality disorder (BPD). Finally, in the last section, we discuss some of the implications of our emotion regulation perspective for clinical assessment and intervention.