The GoldSim Reliability Module allows you to probabilistically model the evolution and performance of complex engineered systems over time. In addition to producing standard reliability metrics, the module also catalogs and analyzes failure scenarios to identify key sources of unreliability and to support risk analysis. Because the Reliability Module is an extension to GoldSim, a general-purpose simulation framework, the system being modeled can evolve into any feasible state and its properties can change suddenly or gradually as the simulation progresses. This facilitates simulation of the operating environment and the calculation of user defined performance metrics.