The Discrete Event Systems Specification (DEVS) formalism developed by Zeigler supports specification of discrete-event models in hierarchical, modular form. Such hierarchical, modular specification offers a basis for the reusable model base, thereby enhancing productivity and quality in modeling engineering. The DEVS-Scheme implements the DEVS formalism in a LISP-based object-oriented programming environment that supports development of highly reusable model bases by using the DEVS formalism and object-oriented framework. This article describes a methodology for developing reusable models in the DEVS-Scheme environment. To develop highly reusable models in a hierarchical, modular manner, the methodology exploits inheritance and encapsulation from the object-oriented paradigm and the hierarchical, modular framework from the DEVS formalism.