Cystic fibrosis (CF) is the most common life-limiting inherited illness of whites . Most of the morbidity and mortality in CF stems from impaired mucociliary clearance leading to chronic, progressive airways obstruction and damage. Significant progress has been made in the care of patients with CF, with advances focused on improving mucociliary clearance, minimizing infl ammatory damage, and managing infections; these advances include new antimicrobial therapies, mucolytic and osmotic agents, and antiinfl ammatory treatments. More recently, researchers have targeted disease-causing mutations using therapies to promote gene transcription and improve channel function, which has led to impressive physiologic changes in some patients. As we develop more advanced, allele-directed therapies for the management of CF, it will become increasingly important to understand the specific genetic and environmental interactions that cause the significant heterogeneity of lung disease seen in the CF population. This understanding of CF endotypes will allow for more targeted, personalized therapies for future patients. This article reviews the genetic and molecular basis of CF lung disease, the treatments currently available, and novel therapies that are in development.