The field of Rehabilitation Psychology codified a group of Foundational Principles that are grounded in clinical and practice efforts as well as the social psychology of disability. These principles are drawn from the work of the social psychologist, Kurt Lewin, his student, Beatrice A. Wright, and her colleagues, who founded and shaped the field of rehabilitation psychology. The Foundational Principles include (a) the person-environment relation, (b) the insider-outsider distinction, (c) adjustment to disability, (d) psychological assets, (e) self-perception of bodily states, (f) human dignity, and (g) advocacy, including self-advocacy by people with disabilities and that conducted by allies. These principles can help disabled persons develop a positive disability identity while also promoting or maintaining resilience when encountering obstacles and challenges linked to disability. For their part, non-disabled people can reduce their ableist beliefs and become allies by becoming familiar with the Foundational Principles. The book reviews the history, role, and potential application of the Foundational Principles for fostering resilience, health, and well-being among individuals with disabilities. The importance of viewing disability as a form of diversity will also be emphasized, including its intersectional nature; that is, individuals with disabilities connect to a wide range of demographic groupings, including race, ethnicity, gender identity, gender expression, sexual identity, sexual expression, religious beliefs, and social class.