Many patients with advanced cystic fibrosis (CF) lung disease receive intensive treatments such as noninvasive and invasive mechanical ventilation for respiratory failure after little or no communication with physicians. Using surveys and follow-up interviews, physicians at two major CF care centers reported their practices for discussing intensive treatment preferences with patients with CF and about barriers and facilitators to communication. Surveys were completed by 30 (88%) and 26 (76%) of 34 eligible CF physicians who provide care for children (60%), adults (23%), or both (17%). Respondents described variable timing and content of discussions. They identified patient/family factors such as denial of disease severity, optimistic expectations of treatment outcomes, inability of ill patients to participate in discussions, and family disagreements about treatments as primary barriers to discussions. They also acknowledged physician factors, including concern for taking away hope and uncertainty about when to address treatment preferences. Patient/family factors were also the most common facilitators identified, particularly disease severity and inquiry about intensive treatments. They recommended: (1) developing standards for communication, (2) offering training in communication for physicians, (3) creating decision support tools for patients and families, and (4) using the multidisciplinary CF care team to facilitate communication. CF physicians describe numerous patient/family factors barriers to communicating about intensive treatments for respiratory failure. They recommend changing physician and organizational factors to improve practice and promote effective communication. Innovation in clinical training, team roles, and decision support may prompt changes in practice standards.