Patients who have had destruction or other disease of the nerves which activate their muscles develop varying degrees of loss of muscle-power known as palsy or paralysis. When a nerve is pressed or cut, it usually heals in such fashion as to permit return of muscle-power. During the period of its impairment, there is not only a loss of power, but frequently concomitant disturbance in the skin, the joints and still other functions. As a result of the nerve disturbance or the disuse which follows, the portion of the body which is paralyzed loses the ability to use its muscles with facility and maximum economy. There are almost no motions performed by single muscles. Most activity results from the contraction of a group of muscles and these are usually in delicate balance with other groups of muscles which either assist or prevent overaction. The delicate adjustment of muscle groups, which is normally present, results in co-ordinated movements. Following nerve disease or, for that matter, the immobilization of joints and muscles, co-ordination is usually lost to more or less degree. Muscles must be re-trained to work together. Such co-ordination can be accomplished by special exercises, but even more rapidly and efficiently by imitating the motions of life. This is the aim of functional occupational therapy. There are other disease conditions which can profit from the use of occupational therapy. These include other disabilities which are accompanied by loss of power, motion or co-ordination. When the skin is burned, healing is usually accompanied by some degree of scarring. If the scar includes a joint on its flexor surface (i.e. inside the bend) there will result a deformity known as a flexion contracture. If nothing is done about this, the crippling process will become progressive and some day reach a stage beyond correction other than that offered by plastic surgery. The early stretching of such joints will not only prevent progressive disability but may result in some improvement. Many other indications for the use of occupational exercise will be met, but since this is not a text on medicine, the preceding types of disabilities will serve as examples of the conditions commonly seen. The crafts first used in functional work were carry-overs of those most beneficial in mental disease, and for the most part were restful and simple, such as basketry, weaving and the graphic arts. More recently, almost all the arts and crafts have been used, as well as motorized tools.