The prevalence of substance use disorder (SUD) is similar among individuals with intellectual or developmental disabilities (ID/DD) and the general population, yet there is a disparity between treatment and outcomes for these two groups due to a lack of appropriately adapted treatment and staff training. The purpose of this case study was to examine how leaders in a behavioral health organization understand the engagement and training experience for staff who provide substance abuse treatment for individuals with ID/DD. Governance and operational data were collected and analyzed from internal archival sources and organizational leader interviews. Themes identified from coding indicated that workforce engagement and training were influential factors in performance efficacy and long-term commitment to the program and agency. Communication challenges interfered with stakeholder information sharing and relationship building. These challenges negatively impacted workforce engagement, training, and performance. Recommended strategies may contribute positively to the organization’s capability and capacity to serve more individuals, increase public awareness of the prevalence of SUD among individuals with ID/DD, and these individuals’ positive social impact as contributing members of their communities.