Inclusive research combines the expertise of academically trained researchers with the lived experience of individuals with disabilities to render results that are more accessible, accountable, and meaningful to the disability community. In this case study, adults with intellectual and developmental disabilities (IDD) contributed as co-researchers to a series of studies on mental health of adults with intellectual disability. The research model, specific engagement strategies, and lessons learned are shared. Feedback from members of the research team suggests that including adults with IDD as co-researchers benefited investigators, co-researchers with IDD, and project outcomes. Our case study emphasizes the valuable contributions of research partners with IDD and provides a model that may be adapted and utilized by researchers to enhance their practice.