Cystic fibrosis (CF) remains the most common genetically inherited disease in the white population and its prognosis is affected by nutritional status. Adults with the disease are now surviving longer and new strategies are required to ensure that they maintain optimal nutrition. This article reports preliminary data from a randomized controlled trial of a 10-week home-based behavioral nutrition intervention, "Eat Well with CF." Outcome measures of weight change over 6 and 12 months and changes in CF-specific nutrition knowledge score, self-efficacy score, reported dietary fat intake and health-related quality-of-life score were compared between the intervention group (n=34) and a standard care control group (n=34). The hypotheses to be tested were that adults with CF completing "Eat Well with CF" would have an improved nutritional status, improvement in specific nutrition knowledge, and an improvement in self-efficacy regarding their ability to cope with a special diet, compared to those receiving standard care. There were substantial improvements in the intervention group's specific CF nutrition knowledge score, self-efficacy score, and reported fat intake compared to control, but no substantial change in body mass index or health-related quality of life over time. Home-based nutrition education incorporating behavioral strategies can be an effective way to support adults with CF, enabling improvement in self-management skills in relation to diet and pancreatic enzyme replacement therapy. This study revealed gaps in basic nutrition knowledge and skills, inadequate knowledge of diet-disease links and pancreatic enzyme replacement therapy. These need to be identified when subjects progress from pediatric to adult care, and programs such as "Eat Well with CF" are a useful adjunct for registered dietitians trying to manage this diverse but growing population.