The number of people diagnosed with depression increased sharply during the second half of the 20th century and is still growing. Depression is one of the leading public health problems in many countries of Europe and the world. This mental disorder can have long-term consequences on personal development, interpersonal relationships and overall quality of life. In the diagnosis and treatment of mental disorders in people with intellectual disabilities, there is a lack of clinical research, financial support of the system, and community awareness and engagement. The emphasis is on understanding depression as a result of social and environmental factors, instead of solely individual characteristics. The role of a multidisciplinary team is essential, as well as tailored therapeutic approaches and family support to improve recognition, treatment and prevention of depressive disorder. A better understanding of the factors associated with depression and anxiety in people with intellectual and developmental disabilities is needed to provide guidance for providers, clinicians, and researchers, as well as to improve the diagnostic process. The aim of this review is to provide an overview of modern scientific research findings on depressive disorders in persons with intellectual and other developmental disabilities, including the frequency of depressive disorders in these persons, risk factors, protective factors, diagnostic assessment and treatment approaches. The paper provides an overview of the concept of the social model of mental health as an alternative to the medical model, focusing on the promotion of inclusion, availability of services, strategies for support, and reduction of stigma and discrimination, all for the purpose of well-being and independence of persons.