Reports of 2022 employment rates demonstrate that while 65.4% of adults without disabilities are employed, only 21.3% of adults with disabilities are employed (U.S. Bureau of Labor Statistics, 2023). Researchers have reported that employees with disabilities are unable to maintain employment often due to difficulty fitting in socially at the workplace (Brickey et al., 1985; Butterworth & Strauch, 1994; Chadsey, 2007; Greenspan & Shoultz, 1981; Kochany & Keller, 1981; Wehman et al., 1982). Since 2009, social skills performance has been identified as a predictor of postschool success (Mazzotti et al., 2016, 2021; Test et al., 2009) meaning that students with disabilities who exited high school were more likely to participate in postschool employment (Benz et al., 1997; Roessler et al., 1990; Test et al., 2009). Social skills challenges have been identified as one potential barrier to obtaining and maintaining employment for adults with disabilities (Bury et al., 2020; Kochman et al., 2017; Parker et al., 2018). While there is a strong link between social skills performance and success in the workplace, there are limited data on the interventions to maintain teaching these skills to adults with disabilities. The purpose of this study was to evaluate the effects of a video modeling and a visual support intervention package on appropriate coworker social skills in the workplace for young adults with intellectual developmental disabilities using a concurrent single-case multiple baselines across participants design. Participants identified as White females ages 21 and 23. I also collected data on participants', coworkers', and the employer's perceptions of this study's goals, procedures, and outcomes. Results of this study indicated a functional relation for one of the two participants. In addition, the participants, employer, and coworkers found the intervention to be socially valid across most measures. The dissertation includes a review of the literature, methods, discussion of each research question, study limitations, directions or future research, and implications. [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.]