General queueing systems are discussed in order to familiarize the reader with the problem. Various access arrangements including straight, graded, slipped, and random access multiples are discussed and compared. Blocking probability curves for slipped multiple access order are generated. Cost of access is discussed. Cost per erlang curves, from which optimum access size is determined, are generated. Algorithms for generating these curves are developed. A stage in a progressive telephone switching system is designed as an example.