A large number of individuals with developmental disabilities (DDs) go undiagnosed with mental health disorders as a result of being predominantly identified by their DDs. This biased treatment is referred to as diagnostic overshadowing and can stem from stigma and lack of education. It is often exacerbated by the inability to directly apply diagnostic criteria to this population. Despite the prevalence of these issues, these concerns are amenable to appropriate intervention, thus improving quality of care. Since social workers typically have a higher rate of contact with clients compared to other health care professionals, they may play a vital role in identifying the possible presence of mental health issues that otherwise have been overshadowed. The current practice note seeks to identify issues concerning the underdiagnoses of mental health issues in individuals with DDs, highlight their impact, and provide modifiable solutions.