Patients will undergo mastectomy and axillary dissection with immediate tissue expander placement. As is the current practice at MSKCC, patients receiving adjuvant chemotherapy will undergo expansion during chemotherapy, with exchange for a permanent implant to be performed approximately one month after chemotherapy and radiation to begin approximately one month after exchange. Patients who receive neoadjuvant chemotherapy will undergo "rapid expansion" of the expander and begin radiation at least 4 weeks following surgery, although it may be performed sooner if the patient has recovered from surgery and the treating physician deems it safe to proceed with treatment. In these patients, exchange for the permanent implant will occur at the discretion of the treating plastic surgeon (approximately 5-8 months after the end of radiation).