Background: Because many patients with cystic fibrosis (CF) continue to survive into adulthood, discussion of end-of-life care decisions between clinicians and patients becomes a crucial part of CF adult care. Advance care planning (ACP) promotes alignment of patient care at the end of life with an individual's goals, however minimal research exists on ACP in CF. Methods: We surveyed adults enrolled in the Project on Adult Care in Cystic Fibrosis (PAC-CF). We assessed experiences with ACP processes and communication and sought to identify factors associated with completion of an advance directive. Results: The mean age of respondents (n ϭ 234) was 34 years and the mean forced expiratory volume in 1 second (FEV 1 ) was 64% predicted. Seventy-four percent reported that they had spoken to someone, generally a family member, about the care they would want if they became too ill to make decisions for themselves. However, only 30% reported completing an advance directive. Although 79% reported feeling comfortable talking to their clinician about ACP, only 28% said that their CF clinicians have asked about ACP. Having specific wishes about treatment decisions (odds ratio [OR] 7.8, 95% confidence interval [CI] 1.9-32.1) and reporting that a clinician had discussed ACP (OR 4.4, 95% CI 1.5-12.6) were significantly associated with reporting the completion of an advance directive. Discussion: Though the majority of adults with CF report thinking about and communicating with family about advance care wishes, only a minority report completing an advance directive. Few adults with CF report being asked about ACP by their clinicians. Formulating specific wishes and discussing ACP with a clinician are strongly associated with completing an advance directive. Efforts to improve clinician communication with CF adults around ACP are needed to ensure that discussion of advance directives becomes an integral component of adult CF care.