Upper respiratory infections are some of the most common reasons for pediatric patients to present to the emergency department. A small percentage of these viral infections can evolve into acute bacterial sinusitis (ABS), which can be further complicated by the development of orbital, intracranial, and osseous complications. Differentiating between viral upper respiratory infections and ABS and identifying cases of ABS that require antibiotics can pose a challenge. This issue highlights the patterns of illness that are most consistent with ABS, based on the most current clinical practice guidelines. Additionally, this issue reviews clinical features that should raise suspicion for complicated disease and provides associated diagnostic and management pearls.