Regulatory agencies in the United Kingdom and United States have been critically examining the possible link between suicidality and antidepressant use in children and adults, which has resulted in an FDA directive to the manufacturers of all antidepressant medications to add a 'black box' warning that describes the increased risk of suicidal behaviour in children and adolescents who take antidepressants. A crucial issue in this debate, as we discuss here, is the assessment of the capacity of antidepressants to increase suicidality over and above what is caused by the underlying disorder, major depression, which is itself the principal cause of suicide.