How do those in power decide to include and exclude those at the margins from community life? We used simulated review of research vignettes to examine how researchers and members of Institutional Review Boards make decisions concerning the research participation of adults with and without intellectual disabilities. Results indicate that decision-makers are influenced by the disability status of the sample, characteristics of the research in which they are engaged, and their attitudes toward the research participation of adults with intellectual disabilities as well as their own relationship to the research process. For example, decision-makers may create situations that limit the self-determination of adults with intellectual disabilities and adults without disabilities within the research context, particularly when the research poses some risk of harm to participants. Implications for theory, action and research are explored.