The publication of the third edition of the Handbook of Mental Health and Aging marks four decades since the arrival of the inaugural edition. Supported by the National Institute of Mental Health, the first edition aimed to introduce the readers to the brand new field of Geriatric Mental Health, with the goal of providing an overview of topics within a field predicted to grow in significance. The editors’ predictions proved correct, and the book provided a foundational background for practitioners and researchers to understand the broad range of factors associated with mental health care in older adults. By the publication of the second edition in 1992, the field of geriatric psychiatry had blossomed, as evidenced by the creation of multiple journals such as the American Journal of Geriatric Psychiatry and International Journal of Geriatric Psychiatry and increasing contributions to this domain of investigation. The editors captured this excitement, providing an integrated review of mental health in older adults. With 33 chapters, the authors provided a broad spectrum of content, including but not limited to age-related neurochemical changes in the brain, mood disorders in older adults, and an introduction on how to provide environmental interventions for cognitively impaired older adults. This second edition established itself as essential within the field, serving as the definitive reference work for researchers, clinicians, and advanced students working within mental health.