This chapter describes the creation of an instrument providing comprehensive assessment of emotional disorder symptoms. The original Inventory of Depression and Anxiety Symptoms (IDAS) was created to address limitations associated with older measures of these disorders. The original IDAS contained symptom scales assessing depression (General Depression, Dysphoria, Suicidality, Lassitude, Insomnia, Appetite Loss, Appetite Gain), anxiety (Panic, Social Anxiety, Traumatic Intrusions), anger (Ill Temper), and positive mood (Well-Being). The Expanded Form of the IDAS (IDAS-II) subsequently was created to provide additional coverage of anxiety (Claustrophobia, Traumatic Avoidance), obsessive-compulsive (Checking, Ordering, Cleaning), and bipolar (Mania, Euphoria) symptoms. The IDAS-II scales are internally consistent and stable over short time intervals. Most scales show substantial elevations in clinical samples. Structural analyses of the IDAS-II scales reveal three underlying factors: distress, obsessions/fear, and positive mood. Finally, nationally representative norms are presented for the IDAS-II scales.