Psycho-oncology is an interdisciplinary field at the intersection of physical, psychological, social, and behavioral aspects of the cancer experience for both patients and caregivers. Also known as psychiatric oncology or psychosocial oncology, researchers and practitioners in the field are concerned with aspects of individuals' experience with cancer beyond medical treatment, and across the cancer trajectory, including at diagnosis, during treatment, transitioning to and throughout survivorship, and approaching the end-of-life. Founded by Jimmie Holland in 1977 via the incorporation of a psychiatric service within the Memorial Sloan Kettering Cancer Center in New York, the field has expanded drastically since and is now universally recognized as an integral component of quality cancer care. Cancer centers in major academic medical centers across the country now uniformly incorporate a psycho-oncology service into their clinical care, and provide infrastructure to support research efforts to advance knowledge in the field.