There is considerable evidence that various psychiatric conditions can be prevented through the implementation of effective evidence-based interventions. Since a large proportion of lifetime mental illness starts before adulthood, such interventions are particularly important during childhood and adolescence. Prevention is important for the sustainable reduction of the burden of mental disorder since once it has arisen, treatment can only reduce a relatively small proportion of such burden. The challenge for clinicians is to incorporate such interventions into non-clinical and clinical practice as well as engaging with a range of other service providers including public health. Similar strategies can be employed in both the European and global contexts. Promotion of mental well-being can prevent mental disorder but is also important in the recovery from mental disorder. This guidance should be read in conjunction with the EPA Guidance on Mental Health Promotion. This guidance draws on preparatory work for the development of England policy on prevention of mental disorder which used a wide range of sources.