Financial/nonfinancial disclosures: The authors have reported to CHEST the following conflicts of interest: Dr Konstan has been a paid consultant during the past 3 years to Boehringer-Ingelheim, CSL-Behring, Genentech, GlaxoSmithKline (GSK), Gilead, NanoBio, Nektar, Novartis, PTC Therapeutics, Transave, and Vertex. He is a member of a scientific advisory board for Aradigm and Genentech and has participated as a speaker for Genentech and Roche. Dr Accurso has received grants from pharmaceutic companies for the conduct of clinical trials. He has received grant monies from the National Institutes of Health (NIH), the Cystic Fibrosis Foundation (CFF), and the CFF Therapeutics for the conduct of research. He has received one honorarium from Inspire Pharmaceuticals for one speaking activity. Dr Ashlock declares, in the general course of her work in the field of CF and therapeutics discovery and development, that she participated, and will likely continue to participate, as an advisor, speaker, and consultant for various events related to the and general subject of this manuscript. In some instances, these events have been sponsored by, or the work has been performed for, commercial entities that perform clinical trials in CF. Dr Clancy has received grant funding from the NIH, CFF, and Maternal Child Health Bureau to support investigator-initiated research projects. He has also received grants from industry to support the conduct of clinical trials. These companies include Vertex, PTC, GSK, Transave, Gilead, Inspire, Novartis, and Kalabios. Dr Rowe receives research grants from the NIH and the CFF, and contracts for clinical trials from PTC Therapeutics and Vertex Pharmaceuticals, and has provided consulting services for PTC, Vertex, and CFF. Drs Solomon, Wilschanski, Billings, Sermet-Gaudelus, Vermeulen, Hill, and Mayer-Hamblett, and Mss Levin, Hathorne, Reeves, and Sabbatini have reported that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.