Abstract: A system and method for simulating the operation of biochemical networks includes a computer having a computer memory used to store a set of objects, each object representing a biochemical mechanism in the biochemical network to be simulated. Most objects have one or more associated signals, representing quantities or concentrations of associated proteins, positions of associated molecules, or other information concerning the state of a biochemical network. Each object has an associated set of methods. These methods include methods for determining reaction probabilities for biochemical reactions associated with the objects, and reaction simulation methods for simulating performance of those biochemical reactions.