This technical report presents a complete user manual describing DESPOT DESign Performance OpTimization, a FORTRAN IV computer program with capabilities extending to 1 preliminary evaluations of solid rocket propulsion units 2 two-dimensional round earth trajectory analysis and 3 parametric trade-offs on the computed design andor trajectory by the Variation-of-Parameters Optimization Techniques. In addition, the program can provide the necessary sybsystem constraining data that are prerequisite to the design of the warhead and the guidance missile subsystems. The rocket design computational algorithms interrlate 21 propulsion subsystem parameters seven of which are input and the remaining 14 calculated. Restricitons imposed on the selection of input parameter combinations prevent over-definition of the missile system. There are five guidance maneuvers, five termination options, and 16 parameter contraints that may be imposed on the trajectory. Liquid rockets can be accommodated by the trajectory routine. The optimization technique can treat 28 rocket design parameters and seven trajectory parameters. The optimum criteria consists of maximum or minimum flight time, range, velocity, flightpath angle, and altitude. The design, trajectory, and optimization routines can be executed individually or in combination, forming an iterative scheme relating design criteria with performance evaluation. Extent of output varies from a cursory description of results to more elaborate digital plots of trajectory and optimization calculations. Instructions for data entry, execution, and redefinition of computational logic are contained in this report.