The use of occupational therapy in mental or physical illness, as an adjunct to medical treatment, has developed rapidly during the past twelve years. As definitions often prove a snare to the uninitiated, and as no comprehensive phrase has been coined for this scientifically applied activity, it seems advisable to give a short survey—based largely on experience gained in the United States—of the manner and degree in which this therapy is contributing to the recovery of the sick to-day.