The global burden of disease associated with mental disorders is increasing, making the prevention and optimal treatment of these disorders a public health priority. Recent years have seen the establishment of several large strategic programs and organizations that aim to reduce this burden. One of these is the Alliance for the Prevention of Mental Disorders (APMD), which supports a population health approach to the prevention of mental disorders through advocacy, the facilitation of research, and the strengthening of knowledge translation and exchange between researchers and policy makers. This cross-journal article collection in BMC Medicine and BMC Psychiatry, titled Prevention of Mental Disorders, is the result of an APMD initiative and outlines the evidence, opportunities and targets for prevention interventions in the workplace, in early life and at the population level. These papers highlight the necessity for comprehensive policies for the prevention of mental disorders, and provide guidance for policymakers and other stakeholders on the implementation of evidence-based initiatives that will help reduce the burden of disease related to mental disorders. All articles in this cross-journal collection have been independently prepared by the authors and have been subject to the standard peer-review processes of the journals.