Development of an intelligent computer-assisted instructional (ICAI) system requires a multidisciplinary team effort. A schematic model is proposed to help ICAI developers identify the types of required expertise and integrate them into a system. Three types of expertise are discussed in the model: (a) domain expertise, (b) domain engineering expertise, (c) and instructional expertise. Domain expertise is classified into two types: conceptual knowledge and performance (procedural) expertise. Specific knowledge representation methods are proposed to represent the two types of domain—semantic network for conceptual knowledge and production rules for procedural knowledge—and frames-scripts for the combined domain of the two types. For domain engineering expertise, three technical methods are discussed: knowledge acquisition, task analysis, and knowledge representation. For instructional expertise, conceptual issues and technical methods to model student learning and to select instructional strategies are discussed. A multidisciplinary cooperative effort is reemphasized in the conclusion.