Government data suggests that 8% of 5 to 10-year-olds and 12% of 11 to 16-year-olds may have a clinically diagnosed mental health condition. For many, their problems may have begun in the early years. Young children can show clear signs of emotional issues at a very early age, including signs of anxiety or depression, post-traumatic stress, attention-deficit or hyperactivity disorders and autistic spectrum disorders. Nursery staff must pay attention to these signs and act accordingly. Organisations such as the Mental Health Foundation firmly believe that many mental health problems in children are preventable and that there is considerable scope for intervention by early years care givers. What are some of the most effective actions that early years staff can take to promote good mental health in the under 5s and support families affected by mental health issues? Martin Hodgson investigates.