In this paper, we discuss the design and use of an object-oriented framework for simulating multi-echelon inventory systems. We present a context for how the framework can be used through its application on two examples. In addition, we describe the design by examining the major conceptual artifacts within the object-oriented model. The framework is built on a Java Simulation Library (JSL) and permits easy modeling and execution of simulation models. The results and discussion indicate the flexibility and power of modeling with the framework. In addition, we summarize our future research efforts to model complex supply chains.