The rehabilitation engineering professions include rehabilitation engineers, rehabilitation technologists / assistive technologists and rehabilitation technicians. The purpose of this white paper is to define the rehabilitation engineering professions, describe educational pathways for the field of rehabilitation engineering, and describe the role of the rehabilitation engineering professions in a multitude of professional settings. An ad-hoc committee was convened by the Rehabilitation Engineering and Technologists (RE&T) Professional Standards Group (PSG) at the 2013 annual meeting, RESNA Conference in Seattle, Washington. The ad-hoc committee reviewed over 80 different sources in preparing the white paper, which included peer reviewed journal articles, conference proceedings, professional organization websites. Based on this review, in addition to expert opinion and stakeholder feedback, the committee developed the following definitions. Rehabilitation Engineer (RE) uses the innovative and methodical application of scientific knowledge and technology to design and develop a device, system or process, which is intended to satisfy the human needs of an individual with a disability. Rehabilitation Technologist / Assistive Technologist (RT/AT) combines scientific and engineering knowledge and methods with technical skills to complement engineering activities for an individual with a disability. Rehabilitation Technician (RTn) works with equipment, primarily assembling and testing component parts of devices or systems that have been designed by others for individuals with disabilities; usually under direct supervision of a rehabilitation engineer or rehabilitation technologist / assistive technologist. Their preferences are given to assembly, repair, or evolutionary improvements to technical equipment by learning its characteristics, rather than by studying the scientific or engineering basis for its original design. This whitepaper provides a framework for future discussions on the advancement of the rehabilitation engineering professions with the goal of improving the quality of life of individuals with disabilities through the application of science and technology.