This publication represents the second volume of the guidelines from the American Society of Breast Surgeons, the Society of Breast Imaging, and the College of American Pathology on the management of benign breast diseases and addresses infectious and inflammatory breast conditions during breastfeeding: lactational mastitis (LM), granulomatous mastitis (GM), and periductal mastitis with squamous metaplasia of the lactiferous ducts* (PDM-SMOLD).