Uncontrolled severe chronic rhinosinusitis with nasal polyps (CRSwNP) is the most bothersome phenotype of chronic rhinosinusitis; it is typically characterized by a type 2 inflammatory reaction and by comorbidities, including asthma, nonsteroidal anti-inflammatory drug–exacerbated respiratory disease, and allergies. Here, the European Forum for Research and Education in Allergy and Airway Diseases proposes structured definitions to enable communication between clinicians and provides a practical algorithm to define type 2 inflammation in CRSwNP in daily clinical practice. A rational approach for the treatment of uncontrolled severe CRSwNP is discussed; it consists of evaluating the perspective and risks of surgery and efficacy and adverse events of biologics on the basis of currently available data. Further, possible combinations of surgery and biologics are discussed, and a rationale is provided. Here, it is of importance to adequately counsel the patient about both approaches to enable a decision-making process with an informed patient. Criteria for the selection of a biologic drug are provided, as several biologics for uncontrolled severe CRSwNP will be available in many countries within a short time. Further, suggestions for monitoring of the drug effects that support recognition of responders to the therapy and, subsequently, the decision regarding continuation or discontinuation of the biologic are proposed.