Pulmonary hypertension (PH) is common in adults with congenital heart disease and carries fundamental implications for management and prognosis. A high index of suspicion, combined with knowledge of the pathogenesis and pathophysiology of PH, is required to achieve a timely, accurate diagnosis, and appropriate classification and treatment. This article provides a guide on how to approach the adult with congenital heart disease and suspected PH of different types, including current management.