A better understanding of the factors associated with depression and anxiety in people with intellectual and developmental disabilities (IDD) is needed to provide guidelines for service providers, clinicians, and researchers as well as to improve the diagnostic process. The current study used a longitudinal dataset to explore demographic, health, and psychosocial risk factors of anxiety and depression in adults with IDD. Women were more likely to have depression while older adults, people with autism, and people with hearing impairments, were more likely to have anxiety. Chronic health conditions were associated with both anxiety and depression, while changes in stressful life events were associated with an increased risk of anxiety. Clinical and research contributions are discussed.