Cancer causes pain as it invades bone, compresses nerves, produces obstructive symptoms in the pulmonary, gastrointestinal, and genitourinary systems, and distends involved visceral organs. This manuscript reviews progress in cancer pain management during the past 2 decades. Since the 1980s, we have seen (1) genuine advances in research on the biology of pain, (2) new approaches to the treatment of cancer pain, and (3) important changes in the health-care system to ensure that pain is appropriately assessed and managed. Currently, clinicians have the appropriate diagnostic and therapeutic tools to ensure that the vast majority of patients with cancer pain can be comfortable during their illness. Nevertheless, too many patients with terminal malignancies continue to die in pain in nations around the globe. An effective strategy to make alleviating pain a major health-care priority remains the primary challenge to effectively palliating patients with cancer pain.