The evolution of the American Congress of Rehabilitation Medicine (ACRM) began in the 1930s with a founding focus on a single emerging modality and now boasts a position as the largest multidisciplinary-centered rehabilitation organization in the country. ACRM was first a medical academy for x-ray therapy, broadened to more physical therapies, then focused in on physical medicine, and finally extended outward again to address both physical and psychological issues. Core disciplines are medicine, physical therapy, occupational therapy, and psychology. The door is not shut. Anyone can join.