Behavioral and academic interventions for individuals with developmental disabilities have been based primarily on behavior theory and principles of applied behavior analysis, with a recent emphasis on positive behavioral supports and the use of nonaversive interventions. Despite the wide acceptance of applied behavior analysis technology within the scientific and academic communities, challenging behavior exhibited by individuals with developmental disabilities remains a serious problem, primarily because interventions based on these principles are inconsistently implemented. This study investigated the relation of knowledge, control style, and attributions with the emotional responses and intervention selection of special education staff who work with students with developmental disabilities and challenging behavior. Specifically, this study investigated social-cognitive variables that may impact staff mediators' potential emotional reactions and behavioral intervention responses following a video stimulus of a student engaging in an episode of seriously challenging behavior. Ninety-two special education staff were surveyed. Lower behavioral knowledge and custodial control orientation predicted higher endorsement of highly restrictive, restrictive, and moderately restrictive interventions. More importantly, interactions of knowledge and social-cognitive variables predicted social-emotional reactions, intervention selection, and ratings of behavior severity. Implications of these results on the training of staff mediators 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.]