This paper describes a simulation study of assigning attainable or predictable due-dates in hypothetical labor and machine constrained job shop settings of varying size and structure. Several predictable due-date assignment rules are developed based on conditional estimates of individual job flow time derived from initial simulation runs. Mean lateness, mean earliness and mean missed due-dates are used as measures of shop performance to compare the various predictable due-date rules under conditions of varying dispatching rules and shop size and structure. Results indicate that due-dates assigned based on expected job flow time and shop congestion information may provide more attainable due-dates than rules based solely upon job characteristics. In addition, better due-date performance appears to be achieved when due-date oriented dispatching rules are employed and when the shop system is not structurally complex.