Inverted papilloma is a benign sinonasal tumor which is locally aggressive and has a significant malignant potential. This report updates the experience of the two senior authors, who have treated 112 patients with inverted papilloma at the Mount Sinai Medical Center over a 20-year period. As clinical examination often underestimates tumor extent, preoperative radiographic assessment is of paramount importance in guiding selection of surgical therapy. Complete en bloc excision via lateral rhinotomy and medial maxillectomy was the method of treatment in the majority of patients (84%). In selected patients with limited disease, or in patients who refused en bloc excision, conservative therapy employing intranasal or transantral ethmoidectomy was performed. The recurrence rates for the two groups were 14% and 20%, respectively. Recurrent disease developed throughout the paranasal sinuses, with the maxillary antrum and ethmoid labyrinth constituting the major sites. In two patients presenting with anterior skull base erosion, craniofacial resection was undertaken to eradicate disease. The latter cases underscore the aggressive nature of the tumor if left untreated. The overall rate of squamous carcinoma in this series was 5%. Given the predilection for local recurrence, multicentricity, and the possibility of malignancy, the authors continue to recommend lateral rhinotomy and medial maxillectomy as the standard therapy for the majority of cases. Management principles as well as a review of the literature are discussed.