Some have argued for a common language in the field of instructional design in an effort to reduce misunderstandings and simplify a multitude of synonymous terms and concepts. Others feel that this goal is undesirable in that it precludes development and flexibility. In this article we propose an ontology-building process as a way for readers to compare and analyze terms and concepts across theories. This process entails the development of categories that emerge from the literature, and the comparison of theories across categories. Such a process can reveal broader concepts that exist beyond specific theoretical terminology, differences in meanings behind common terms used by theorists, a greater understanding of the theorists' intent, and discontinuities and gaps within the theoretical literature.