This playful and practical handbook presents one of the first clinically tested treatment protocols for Functional Abdominal Pain (FAP) in young children. Created and tested by Dr. Nancy Zucker with support from the National Institutes of Health, this intervention teaches children to become "FBI agents" (Feeling and Body Investigators) - detectives who investigate and learn to manage their symptoms. Kids develop a newfound trust in their bodies by using strategies that transform fear and confusion into curiosity and humor. This clinical manual provides a detailed step-by-step guide to treatment, including session plans, worksheets and activities, and is supplemented by diagrams, excerpts from case dialogues, references and cartoons. Downloadable full color materials are available online to print and use in individual or group sessions. Offering an effective and fun approach firmly rooted in science, this manual guides clinicians in implementing FBI in their own practices, enabling more children to access this novel treatment.