This report describes research directed at designing and evaluating computer assisted instructional (CAI) systems capable of inferring structural models of a student's reasoning strategies and identifying his underlying misconceptions. Several prototype systems using representative domains of knowledge were constructed. From these an information processing framework comprising models of expert reasoners, adaptive tutors, and students, have evolved. Section 1 describes two paradigmatic instructional systems involving a decision making and a gaming environment. Section 2 explores issues of building intelligent instructional systems over more complex domains of knowledge. Section 3 describes research related to the design of robust intelligent systems. (Author/WBC)