Pulmonary hypertension (PH) can occur as either a primary or a secondary process, and in general, its presence increases overall morbidity and mortality. Importantly, the majority of prior studies have been in the setting of idiopathic pulmonary arterial hypertension (IPAH); thus the following discussion focuses on IPAH. Because the majority of available diagnostic strategies lack sensitivity and specificity, the physician must maintain a high index of suspicion in considering PAH. This article provides an overview of the available diagnostic studies for PAH with a particular focus on hemodynamic assessment. Novel approaches to the often delayed diagnosis of PAH are being studied and are also discussed here.