Financial/nonfinancial disclosures: The authors have reported to CHEST the following conflicts of interest: Dr Elliott is an employee of Intermountain Healthcare, and Intermountain Healthcare has received support from Pfizer, Encysive, Actelion, Eli Lilly/ICOS, and United Therapeutics for contracts on which Dr Elliott is the site Principal Investigator. Dr Elliott serves as a consultant to Actelion as a member of the Steering Committee for the REVEAL registry. Intermountain Healthcare has filed a patent based on Dr Elliott’s invention for the use of BMPR2 mutation analysis to assess vasoreactivity in pulmonary arterial hypertension. Dr Barst has received research grants and/or consultancy honoraria from Actelion, Eli Lilly, Pfizer, United Therapeutics, Novartis, Gilead, and GlaxoSmithKline. Dr Seeger received honoraria in 2006, 2007, and 2008 for speaking at a symposium organized by Bayer Schering Pharma AG, and in 2008 for speaking at a symposium organized by Lung Rx, Inc. He also received payment in 2009 for chairing a research workshop, and payment in 2008 and 2009 for chairing the PHUPDATE organized by Encysive. Dr Seeger received grant support from Lung Rx for a contract on which he is the site Principal Investigator, from Gilead in 2007/2008 for participating in a multicenter clinical trial, and from Lung Rx in 2007/2009. He served as a consultant to Bayer Schering Pharma AG of the Steering Committee for the Ventavis Registry. Dr Zamanian is the recipient of an Entelligence/Actelion career development grant and is a consultant for Gilead and United Therapeutics Pharmaceuticals. Dr Rubin has received grant/research support from NHLBI, Actelion, Gilead, United Therapeutics, and Pfizer; serves or has served on advisory committees for Actelion, Pfizer, and Gilead; and serves or has served as a consultant for NHLBI, Actelion, Pfizer, United Therapeutics, Gilead, Aires Pharmaceuticals, Bayer Schering Pharma AG, MondoGEN, Solvay Pharmaceuticals, GeNO, BioMarin, Cytokinetics, CardioMems, Lexicon, and ErgoNex. He is also a stock shareholder for United Therapeutics and GeNO. Drs Porres-Aguilar and Brown report that no conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.