Background: Young adults (YA) with intellectual/developmental disabilities and co-occurring mental health conditions (MH) are underemployed. One reason may be a lack of accommodations that mitigate the impact of MH challenges at work. We explored common workplace MH impacts and supportive accommodations. Methods: Interviews with YA with intellectual/developmental disabilities and co-occurring MH conditions (n = 12) and focus groups with professionals who support them to attain and maintain jobs (n = 17). YA also completed a survey describing MH impacts and accommodations. Findings: Although individualized, common MH impacts included challenges with attendance, performing and switching between work tasks, feeling overwhelmed, and sensory overload. Participants valued breaks, individualized scheduling, and social supports. Participants endorsed the potential usefulness of several accommodations they had not previously requested. Conclusions: Accommodations should be tailored to each YA. Further, YA may benefit from education about the range of accommodations that may support them to manage their MH symptoms at work.