There is a high prevalence of adults and children presenting at health care services with bodily complaints that do not have an observable physiological cause, for example, pain, dizziness, fatigue, and bowel dysfunctions. A multitude of etiologic and pathogenic mechanisms and contributing factors play a role in medically unexplained symptoms (MUS) and bodily distress, representing a constant challenge to refine models of bodily distress to inform primary and secondary prevention, stepped care intervention, and specialized treatment. This collection of contributions from around the world focuses on research that investigates four key areas: 1) detection and diagnosis, 2) etiologically relevant mechanisms, 3) clinical management and effective treatment, 4) implementation of treatment. Written from various research perspectives in psychology and medicine, this volume shows the necessity of interdisciplinary research to advance our understanding of MUS and bodily distress as a heterogeneous condition.