A shoulder orthosis is provided having an arm support and an optional arm spacer connected to the arm support. The arm support includes an arm retainer and a supportive strapping system. One optional arm spacer includes a pair of individual pillows which are attachably combinable with one another at a first face of the first individual pillow and a face of the second individual pillow to form one combined pillow having a first shape. The individual pillows are alternately attachably combinable with one another at a second face of the first individual pillow and the face of the second individual pillow to form another combined pillow having a second shape different from the first shape.