The study of the dynamics of physical systems is of importance to all engineering students. LSSP, a Linear System Simulation Program, is used to study the behavior of physical phenomena and systems which may be represented to a good degree of approximation by linear models. Emphasis is placed upon the unity resulting from the mathematical representation for many types of physical systems: mechanical, electrical, electromechanical, thermal, etc. The mathematical unity can also result for the study of social systems. This paper presents a user's guide for LSSP and a list of differential equations governing the behavior of physical and social systems. LSSP is an interactive program written in FORTRAN IV. It is composed of ten subroutines and a main routine. The program listing is included. (Author/BB)