This report describes a specific approach to two current trends in Intelligent Tutoring Systems (ITS) research: (1) an emphasis on metacognitive skills which are not domain specific; and (2) a move away from viewing ITS research as being exclusively concerned with "knowledge communication." A human-computer dialogue model designed to teach the metacognitive skill of critical argument is described. The dialogue model occurs in a knowledge domain consisting of a set of justified beliefs, and is exemplified in the domain of teaching musical structures. The model is based on a dialogue planning system that involves higher level planning decisions, making claims and challenges, and understanding the components of dialogue such as actions, effects, and preconditions. Integrating intentional and topical dialogue structures, the model may also be used with a variety of tutorial styles within a guided-discovery tutoring approach. (39 references) (Author/DB)