Belonging is an essential human need, regardless of whether or not one has a disability, and has been found to positively impact one's physical and mental health. Feelings of belonging for college students with intellectual and developmental disabilities (I/DD) have largely been unexplored in research. Using the 10 Dimensions of Belonging framework (Carter & Biggs, 2021) as a foundation in this dissertation, 13 students with I/DD who attended inclusive post-secondary education (IPSE) programs across the United States were individually interviewed to better understand how they perceive their experiences of belonging (or not) on their college campus. To complement the interviews, a subset of four students were observed during a typical college day. Ultimately, interviews indicated that participants in this study experienced all 10 Dimensions of Belonging (i.e., present, invited, welcomed, known, accepted, involved, supported, heard, befriended, and needed), as well as gaps in belonging (i.e., exclusion in places and spaces, unheard, unknown, lack of invitation, extraneous, lack of support, "drama," and lack of friendship with non-IPSE peers). Observational data largely corroborated these findings. Analysis of this data led to a revised model of belonging specifically for IPSE students, as well as recommendations for IPSE programs to increase feelings of belonging for IPSE students. Future research should continue to explore feelings of belonging for IPSE students in other contexts, such as community colleges or in other geographic regions around the world. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]