Purpose: To determine the upstage rate from nonmalignant papillary breast lesions obtained at imaging-guided core needle biopsy (CNB) and if there are any clinical, imaging, or pathologic features that can be used to predict eventual upstaging to malignancy. Materials and Methods: This retrospective case review was institutional review board approved and HIPAA compliant, with a waiver of informed consent. A database search (from January 2001 to March 2010) was performed to find patients with a nonmalignant papillary breast lesion diagnosed at CNB. Of the resulting 128 patients, 86 (67%) underwent surgical excision; 42 (33%) patients were observed with imaging, for a median observation time of 4.1 years (range, 1.0-8.6 years). Chart review was performed to determine pertinent features of each case. Results: Fourteen of 128 patients were subsequently found to have malignancy at excision, for an upstage rate of 11%. Nine (7%) of the 128 patients were subsequently found to have atypia at excision. Comparisons between patients with upstaged lesions and patients whose lesions were not upstaged demonstrated patients with upstaged lesions to be slightly older (65 vs 56 years, P = .01), more likely to have a mass than calcifications at imaging (P = .03), and to have had less tissue obtained at biopsy (three vs five cores obtained, P = .02; 14- vs 9-gauge needle used, P < .01; no vacuum assistance used, P < .01). Most strongly predictive of eventual malignancy, however, was whether the interpreting pathologist qualified the benign diagnosis at CNB with additional commentary (P < .01). Conclusion: Given the substantial upstage rate (11%) of papillary lesions diagnosed at imaging-guided CNB, surgical excision is an appropriate management decision; however, careful evaluation in concert with an expert breast pathologist may allow for observation in appropriately selected patients.