Breast conserving therapy, (BCT), which consists of wide local excision of the tumor followed by 6 weeks of whole breast irradiation, (WBI), is integral to the management of breast cancer. Evidence now suggests that WBI may not be necessary and treatment to the involved area only, partial breast irradiation, (PBI), may suffice. PBI can be achieved by interstitial or intracavitary brachytherapy, intra-op, or post op external beam radiation therapy. The feasibility, toxicity and efficacy of PBI are currently being studied in both the U.S. and Europe. Review of smaller studies suggests that PBI will prove to be comparable to WBI. Chemotherapy combined with radiation has been shown to increase local control in BCT when compared to radiation alone. However there is little data on how sequencing or timing of these therapies with respect to one another affect outcome. As a result there is no consensus about the optimal combination. There are real and potential benefits to concurrent chemo-radiation therapy. Concurrent therapy 1) allows both treatments to start closer to surgery, theoretically maximizing the benefits of each modality; 2) shortens the overall treatment program; and 3) may also improve local control via chemo-sensitization of residual cancer cells. However, concurrent chemotherapy and WBI have been associated with prohibitive skin toxicity. Since less breast tissue is treated with PBI, this skin toxicity may no longer be prohibitive. We have shown in J0381 that PBI and concurrent dose dense AC is safe. As a follow-up, we propose a phase I/II trial addressing the toxicity and efficacy associated with PBI delivered concurrently with various chemotherapy regimens.