Chronic rhinosinusitis (CRS) is characterized by infection and inflammation of the nose and paranasal sinuses. CRS in children with cystic fibrosis (CF) is a challenging clinical condition and requires unique approaches to evaluation and both medical and surgical treatment. As the pathogenesis becomes clearer through ongoing clinical and basic science research, however, our ability to treat CRS in children with CF both effectively and safely should continue to improve. A number of studies over the past few years support the concept of the unified airway theory, suggesting an important relationship between disease and bacterial pathogens of the sinuses and the lower respiratory tract. While surgery, including adenoidectomy and functional endoscopic sinus surgery (FESS), can be beneficial in pediatric CF patients with CRS, the effect of surgery on lung pathogens and pulmonary function remains an area for further investigation. Knowing when a child with CF and CRS is likely to benefit from surgery can be difficult. In this chapter, we review the pathogenesis, evaluation, and treatment of CRS in children with CF and propose a framework for surgical decision-making based on outcomes for nasal polyposis, CRS symptoms, and pulmonary function.