This essay explores the self-deficit nursing theory by Dorothea Oream, its application in healthcare, and the biography of the theorist. The theory emphasizes the importance of patients' involvement in their own care for a fast and holistic recovery. It also highlights the role of nursing care when patients' self-care needs exceed their ability to take care of themselves. The essay provides examples of how the theory can be applied in healthcare settings, such as caring for children with disabilities and asthma. The impact of the theory is international and continuously evolving.