Simulation offers unique affordances over traditional training (e.g., remote access, mastery learning experiences, immediate feedback) relevant to teacher training in behavior management. This study describes a user-based evaluation of Interactive Virtual Training for Teachers (IVT-T). The study involved observing representative users (seven advanced education majors) perform benchmark tasks with the system, complete rating scales, and participate in interviews to evaluate the usability and instructional design quality of IVT-T. Global usability ratings based on established usability rating scales suggested IVT-T was adequately usable while observations of user performance and semi-structured interviews revealed design shortcomings that impeded effective user performance and informed ways to improve the interface. Observations of user performance, for example, identified 36% of usability problems related to learning, 19% = screen design, 17% = terminology; 3% = system capabilities and 25% = other problems. Cross analysis of user semi-structured interviews pointed to the system's ability to convey believable, visually appealing, realistic characters and classrooms. More contextual cues, multiple challenging behaviors featured at the same time, and changes to the visual appearance of the classroom would enhance realism. Revisions made to enhance the usability and instructional design elements of IVT-T are discussed. In addition, implications for teacher educators and researchers involved in the development of instructional technologies are summarized along with the potential value of including simulation in teacher training for behavior management. [For the corresponding grantee submission, see ED607576.]