The study found that specialist mental health nurse support is no better than support from GPs for patients with anxiety, depression and reactions to life difficulties. The results suggest that healthcare providers could consider adopting policies of restricting referrals of unselected patients with common mental disorders to specialist CMHNs, although there may be other roles in primary care that CMHNs could play effectively. Further research should address the predictors of chronicity in common mental disorders and target extra treatment. More research is also needed into the effectiveness and cost-effectiveness of problem-solving treatment for other disorders, of facilitated self-help treatments for common mental disorders and of CMHN care for people with severe and enduring mental illnesses, as well as the prevention of mental disorders.