Breast-conserving therapy (BCT) is a proven local treatment option for select patients with early-stage breast cancer. This paper reviews pathologic, clinical, and treatment-related features that have been identified as known or potential predictors for ipsilateral breast tumor recurrence in patients treated with BCT. Pathologic risk factors such as the final pathologic margin status of the excised specimen after BCT, the extent of margin involvement, the interaction of margin status with other adverse features, the role of biomarkers, and the presence of an extensive intraductal component or lobular carcinoma in situ all impact the likelihood of ipsilateral breast tumor recurrence. Predictors of positive repeat excision findings after conservative surgery include young age, presence of an extensive intraductal component, and close or positive margins in prior excision. Finally, treatment-related factors predicting ipsilateral breast tumor recurrence include extent of breast radiation therapy, use of a boost to the lumpectomy cavity, use of tamoxifen or chemotherapeutic agents, and timing of systemic therapy with irradiation. The ability to predict for an increased risk of ipsilateral breast tumor recurrence enhances the ability to select optimal local treatment strategies for women considering BCT.