A significant problem for individuals with autism is the presence of stereotypic behaviors, that is, repetitive, invariant behavior patterns with no obvious goal or function. Stereotypic behaviors interfere with an individual's ability to participate in the daily activities of life, including learning. By reducing stereotypic behaviors in individuals in a school setting, the individuals will be more available to participate in learning activities. This study investigated the effects of individually-designed sensory-based interventions, delivered in a multi-sensory environment, on the stereotypic behaviors of students with autism. A multiple baseline design across five participants with autism was used to conduct the experiment. Participants were provided targeted sensory treatment in the multi-sensory environment just prior to group instructional activities. Dependent variables included rate of stereotypic behavior and rate of out-of-seat behavior, expressed as a percentage of intervals during which the behavior occurred across sessions. Results of the study indicated that individually-designed sensory-based interventions, delivered in a multi-sensory environment, reduced the mean rate of stereotypic behaviors for all five participants. Further, the three participants who experienced the greatest reductions in levels and trends in stereotypic behaviors during the treatment phase also experienced delayed effects of treatment during non-targeted activities. Key elements to treatment effectiveness included a structured protocol and the use of sensory and behavioral assessments to develop interventions. Further, participant characteristics may influence treatment effectiveness. These themes, as well as their implications for future research and practice, are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]