GASP II consists' of a set of FORTRAN subprograms organized to assist the systems analyst in performing simulation studies. GASP II formalizes an approach to simulation by specifying common elements of simulation studies and providing subprograms for performing those simulation tasks that are independent of a particular problem. In this tutorial, the structure and subprograms of GASP II will be presented. Examples of the use of GASP II will be presented, which will include the programming required, the input data formats and the resulting summary reports. An introduction to GASP IV, a combined discrete/continuous simulation language will be presented.