This is a retrospective comparative study of two established therapies. It is designed to enroll patients who will be undergoing breast reconstruction with tissue expanders/implants. Two groups will be created. One with patients receiving acellular dermal allograft for submuscular coverage and a second group of patients undergoing dermal autograft for submuscular coverage. Patients with a lower abdominal scar and sufficient abdominal laxity for autograft harvest will be offered this technique. The subset of these patients who elect to undergo autografting will comprise the autograft group. The allograft group will consist of the patients without a suitable abdomen for autografting and those who decline the autograft procedure. Patients in the allograft group will have placement of dermal allograft over the lower pole of the tissue expander. Patients in the autograft group will undergo harvest of a dermal autograft from the lower abdomen at the time of mastectomy, which will be used to cover the lower pole of the tissue expander. The following data will be recorded in an unidentifiable fashion: age, medical history, type of breast cancer treatment, type of reconstruction to include implant type, brand, implant size and characteristics, time of surgery including autograft harvest, and cost of overall procedure. Patients will receive routine follow-up care only, and the presence of any complications will be recorded. Per the standard reconstructive sequence for implant-based breast reconstruction, all patients will undergo a second surgical procedure under general anesthesia approximately three months following the initial surgical procedure for replacement of the tissue expander with a permanent implant and capsulotomy. At the time of this procedure, three small samples of the internal capsule will be harvested from standard locations with a 4mm biopsy punch. Histology with H/E and factor VIII staining will be performed on these samples to measure inflammation, tissue architecture, and vascular ingrowth. Comorbidities between patients with and without acellular dermal matrices will be evaluated using the Fisher exact test. Group differences for continuous variables will be assessed with the t test.