NEUROMECHANIC is a simulated physical environment for developing and testing neural control models. Rigid body dynamic equations of motion, phenomenological muscle models, and simplified neuron models are incorporated. Additional neural models can be prototyped by the user in matlab or in a dynamic linked library. NEUROMECHANIC was specifically developed to answer questions involving neural control and stability; the software linearizes the equations of motion for a given body and posture, evaluates the Lyapunov stability of the system, and performs forward dynamic simulation. In addition to analysis of animal movement the software has been used to develop control strategies for neural-machine prostheses. Soon, Neuromechanic will be able to be used with a tool that predicts the locomotor patterns of animals.