ExtendSim 7 is a proven simulation environment capable of modeling a wide range of systems. ExtendSim 7 is used to model continuous, discrete event, discrete rate, and agent based systems. ExtendSim’s design facilitates every phase of the simulation project, from creating, validating, and verifying the model, to the construction of a user interface that allows others to analyze the system. Simulation tool developers can use ExtendSim’s built-in, compiled language, ModL, to create reusable modeling components. All of this is done within a single, self-contained software program that does not require external interfaces, compilers, or code generators. This paper will introduce ExtendSim 7, demonstrate its advanced technology and features, and explain sample simulation applications.