Breast reconstruction is a common procedure with over 86,000 breast reconstruction procedures performed in the United States in 2009. This is a 1.5-fold increase since 2007. Of these breast reconstructions, 65% use a tissue expander/implant technique. Although satisfactory results can be achieved with a single-stage technique, a two-stage approach is considered more reliable, allowing for precise positioning of the inframammary fold and an opportune time to perform a capsulotomy to increase the breast skin flap by releasing the soft tissue. The placement of the tissue expander and implant under the chest muscles is thought to minimize the incidence of capsular contracture, expander exposure, and in addition, produce acceptable aesthetic results. However, discomfort is often associated with this submuscular placement of a tissue expander or implant, specifically during the expansion phase. Patients undergoing immediate reconstruction using submuscular implants have been shown to have higher analgesic requirements and to have higher pain scores post-operatively, compared to non-reconstructed patients. An uncomfortable reconstruction can lead to under-filling of the expander, a longer expansion process, abandonment of reconstruction, and a compromised quality of life. The use of Botulinum Toxin A (Botox) injections into the chest muscles at the time of surgery may help ease the discomfort that is often associated with this procedure. The investigators propose a prospective double-blind randomized placebo-controlled trial of patients undergoing tissue expander/implant reconstruction. The information gathered from this analysis will provide a greater understanding of the effects of Botox in the setting of two-stage tissue expander/implant breast reconstruction, with the goal to improve patient satisfaction and quality of life.