The purpose of this paper is to operationally define four components of a mental set and describe how students can be taught to be aware of and control their mental set. Parameters of mental set include affect, attitude, focus, and meaning. It is argued that many factors essential to the success of a given task are at least partially, and perhaps greatly, controlled by the affective tone of an individual; the individual's attitudes; the extent to which the individual is goal-directed; and the situational meaning the individual generates. These elements constitute the "context" in which individuals operate from moment to moment. Certain dispositions relative to these parameters "set up" success; others "set up" failure. It is further argued that one of the primary reasons for the breakdown of many classroom learning experiences is poor contextual thinking by students, and perhaps by teachers. While good contextual thinking will not insure knowledge acquisition, its absence will defeat most presentations of content area knowledge. The proposed strategy for contextual thinking, which is meant to be taught and reinforced in the classroom, attempts to make students aware of the four elements of an individual's context, and provide them with a technique for monitoring and controlling the elements in various situations. (RH)