Radiotherapy and surgery have both played prominent roles in the treatment of esophageal cancer since the beginning of the 20th century. Although the use of radiotherapy alone to treat esophageal cancer has a long history, it has not demonstrated improved outcomes compared with surgery alone. The disappointing rates of survival and local control associated with single-modality therapy and the need for effective nonsurgical management led to the development of definitive chemoradiotherapy paradigms for esophageal cancer. Adding cytotoxic chemotherapy to radiotherapy for additive or synergistic effect was described as early as 1968, and over time, treatment has shifted from single-modality therapy toward combined-modality therapy using chemotherapy and radiotherapy. This approach eventually demonstrated superior outcomes in patients with esophageal cancer when compared to radiotherapy alone. Maximum benefit of this therapy depends on the appropriate addition of surgery and the optimization of radiosensitizing chemotherapy. A burgeoning area of research has focused on improving definitive chemoradiotherapy strategies through the incorporation of newer chemotherapeutic agents and targeted biologic agents. An overview of the history of chemoradiotherapy in the treatment of esophageal cancer is presented, as well as a discussion of ongoing studies and future areas of promising research.