Aging increases susceptibility both to psychiatric and medical disorders through a variety of processes ranging from biochemical to pharmacologic to societal. Interactions between aging-related brain changes, emotional and psychological symptoms, and social factors contribute to multimorbidity – the presence of two or more chronic conditions in an individual – which requires a more patient-centered, holistic approach than used in traditional single-disease treatment guidelines. Optimal treatment of older adults with psychiatric and medical multimorbidity necessitates an appreciation and understanding of the links between biological, psychological, and social factors – including trauma and racism – that underlie physical and psychiatric multimorbidity in older adults, all of which are the topic of this review.