The structure of supervisor programs for time shared or multiple access operating systems is described. Those functions of the supervisor that are concerned with scheduling and resource allocation are emphasized. The four time sharing systems that are described are Control Program 67 (CP/67), Time Sharing System (TSS/360), and University of Michigan Multi-Programming Supervisor (UMMPS) for the IBM System 360 Model 67 and Multics for the General Electric 645. The emphasis is on describing and comparing the various supervisor programs, rather than recommending any specific approach. In general those aspects of the supervisor programs that are the direct result of some peculiarity of the hardware used are not included.