When students feel that their learning needs are not being met by computer-aided instruction, learning becomes passive, often resulting in boredom, frustration or a dislike for learning with computers. "Button Theory" allows the student to express his feelings and questions to the computer at the touch of a button, thus enhancing control over the learning process. "Button Theory" is implemented by means of a comprehensive set of messages, which the student can use to interact with and control the computer-based tutor; each message corresponds to one button represented by an icon on the computer screen. In order to examine the feasibility and adaptability of "Button Theory" across different computer-based learning environments, it was implemented in a prototype CAI system on astronomy, Solaria. Thirteen buttons were chosen for implementation in Solaria, and were divided into three categories: feelings, questions, and control. Messages in the questions and control categories were found to be generic, while those in the feelings categories were less so. One implication of this is that the development of a learning environment based on "Button Theory" would be simplified; a core set of conditions or contextual variables on which to select a response to a button press is needed. (AEF)