The EvtGen particle decay simulation package. With several new B-physics experiments now taking data, the physics of B-meson decays will be studied in greater detail than previously possible. It is important to have a simulation of the underlying physics processes that is able to accurately describe this data. The EvtGen package provides a framework for the implementation of physics processes relevant to decays of B mesons and other resonances. Models of time dependent CP asymmetries in neutral B meson decays, semileptonic form-factor models, and a full decay table for B decays are a few of the implemented features.