Period Batch Control (PBC) is Just in Time (JIT) 'Flow Control', single-cycle, Production Control method, based on a series of short standard periods, generally of one week or less. The book describes the advantages of the method. It eliminates the 'Surge effect', it reduces throughput time, stocks and stock holding costs, and it simplifies ordering, operation scheduling and 'Loading', or the control of Load and Capacity. The book describes methods for planning the system; for planning and controlling its introduction, and gives examples of its use in practice. Particular attention is paid to the time constraints such as throughput time and set-up which have to be reduced before PBC can be used. It is shown that PBC is the ideal Production Control method for use with Group Technology (GT). GT makes a major contribution to the reduction of time constraints, thus simplifying the introduction of PBC. PBC on the other hand simplifies ordering, operation scheduling and loading, greatly improving the efficiency of GT.