A soft, passive, multi-joint exosuit was developed for the purpose of lower body augmentation to aid the user with the performance of walking, running, and jumping. Through OpenSim simulations, key muscles at specific joints were identified and analyzed for major contributions in total fiber force and moment created amongst other key factors. Torque results obtained from OpenSim were verified using MATLAB through the implementation of the Newton-Euler method to ensure reliable results. Following simulation, a prototype for the initial design concept was developed.