Occupational therapists in all areas or practice grade therapeutic activities to help patients progress toward their goals. It is proposed in this paper that the concept of graded activity originated in German tuberculosis sanatoria in the late 1800’s, when patients were required to walk on graded (sloped) land for exercise. British physician Marcus Paterson included work, as well as walking, in his graduated exercise program for tuberculosis patients and was honored for this innovation at the founding meeting of the National Society for the Promotion of Occupational Therapy (NSPOT). George Barton, Susan Tracy, and Herbert Hall were among the NSPOT members who contributed to the development of graded activity as a principle in occupational therapy intervention. The military rehabilitation programs established during world War I provided additional impetus, and by the mid-1920s, graded activity was recognized as central to the profession.