The knowledge base in a given domain has an inherent structure within it, corresponding to the interrelationships between concepts, propositions, images, etc. Written language often makes that structure obscure because of its linear format and frequent ambiguities. Graphs can be used to make the structure of knowledge explicit, and this allows for a variety of knowledge engineering procedures and analyses to be performed with or upon the graphs. Conceptual graph structures are a particular type of graph, consisting of nodes and labeled arcs, which can be used to represent both declarative and procedural knowledge. The graphs rely on a highly specific syntax developed by Art Graesser and colleagues over a period of ten years, and have been empirically validated in several domains. The conceptual graph syntax described in this paper is a modified version developed at the University of Idaho specifically for knowledge engineering and instructional design purposes. Conceptual graph structures can be used to represent a variety of types of knowledge including taxonomic knowledge, goal structures with arcs corresponding to if-then rules, spatial knowledge, and causal knowledge. The structures can be used to depict the content and structure of a body of knowledge either for a particular individual or for a domain in general. This representational capability supports a variety of instructional activities including curriculum development and analysis, instructional design and development of instructional materials, and trainee evaluation.