Case management (CM) is one of the most commonly used services by individuals with intellectual and developmental disabilities (IDD), but little is known about the workers who provide CM. This study used a mixed methods approach to gain understanding of the CM workforce in one U.S. state. An online survey was completed by 35 IDD service directors (87.5% of directors in the state); and 113 CMs and CM supervisors participated in semistructured interviews and focus groups. Results indicated an annual crude separation rate of 28.2%, and participants often complained that turnover resulted in caseload sizes that prevented optimal outcomes for people with IDD. A limited applicant pool, duties focused on regulatory compliance, and inadequate wages were cited as major challenges for CMs.