Research indicates a connection between successful outcomes for students with significant intellectual disabilities and the individual education program (IEP) team's efforts in the IEP development process. However, little research has been conducted on the perceptions of parents and teachers of students with significant disabilities about parent participation in the IEP development process. Therefore, the purpose of this phenomenological study was to explore parent and teacher perceptions of parent participation in the IEP development process. The conceptual framework of this study was ecological design theory, based on Bronfenbrenner's theory of human development and Neal and Neal's theory of networked systems. Participants consisted of 4 parents and 5 teachers of students with significant intellectual disabilities who have participated in the IEP development process. The interviews conducted with participants were analyzed for patterns and themes. Findings showed that teacher descriptions centered on actions connected with fulfillment of state guidelines, which create the setting in which the IEP development takes place. Parent participants acknowledged compliance to state guidelines based on teacher actions, but parent commentary was centered on elements of the parent-teacher relationship. Responses indicated that actions to strengthen the school-parent partnership may improve parent and teacher experiences of IEP development. This study contributes to positive social change by providing administrators and teachers information to better support the IEP development process toward improved outcomes for students with significant intellectual disabilities. [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.]