Surgery is an essential component in the management of treatable breast cancer. With the use of standardized staging and data collection, evidence-based management of breast cancer has evolved to limit treatments to what is necessary but sufficient to allow tissue preservation and control of treatment-specific morbidity. As more tumors are discovered by pretreatment imaging and are not identifiable on physical exam, intraoperative tumor localization techniques have become increasingly sophisticated and reliable. Techniques for localization of "sentinel" nodes has become increasingly accurate and technically less complicated. Surgical treatment may occur Note to the reader: This chapter is part of the book Breast Cancer (ISBN: 978-0-6453320-3-2), scheduled for publication in July 2022. The book is being published by Exon Publications,