The most common forms of pulmonary hypertension (PH) are Group II (PH associated with left heart disease) and Group III PH (PH associated with lung disease). Unlike Group I or pulmonary arterial hypertension (PAH), PAH-specific therapy is not effective and is potentially harmful in patients with Group II and III PH. This session will review the different etiologies of PH, the work-up of a patient newly diagnosed with PH and how to distinguish the different PH Groups.