Rhinosinusitis (RS) affects approximately 1 in 7 adults in the United States, and its effect on quality of life, productivity, and finances is substantial. During the past 10 years, several expert panels from authoritative bodies have published evidence-based guidelines for the diagnosis and management of RS and its subtypes, including acute viral RS, acute bacterial RS, chronic RS (CRS) without nasal polyposis, CRS with nasal polyposis, and allergic fungal RS. This review examines and compares the recommendations of the Rhinosinusitis Initiative, the Joint Task Force on Practice Parameters, the Clinical Practice Guideline: Adult Sinusitis, the European Position Paper on Rhinosinusitis and Nasal Polyps 2007, and the British Society for Allergy and Clinical Immunology. Points of consensus and divergent opinions expressed in these guidelines regarding classification, diagnosis, and management of adults with acute RS (ARS) and CRS and their various subtypes are highlighted for the practicing clinician. Key points of agreement regarding therapy in the guidelines for ARS include the efficacy of symptomatic treatment, such as intranasal corticosteroids, and the importance of reducing the unnecessary use of antibiotics in ARS; however, guidelines do not agree precisely regarding when antibiotics should be considered as a reasonable treatment strategy. Although the guidelines diverge markedly on the management of CRS, the diagnostic utility of nasal airway examination is acknowledged by all. Important and relevant data from MEDLINE-indexed articles published since the most recent guidelines were issued are also considered, and needs for future research are discussed.