This study set out to investigate the utility of 4 often referred to behavioural antecedents of suicide attempts--suicide ideation, plans, threats and deliberate self-harm--in the prediction of suicide attempts and the identification of suicide attempters and nonattempters among adolescents. A total of 156 male and 151 female students aged between 14 and 17 years (mean = 15.8) attending one randomly chosen metropolitan state high school completed a questionnaire concerning a number of aspects of suicidal behaviour. The findings indicated that suicide ideation, plans and threats, and deliberate self-harm are associated with suicide attempting and that a combination of suicide plans and deliberate self-harm present a particularly worrying mixture. Further, a composite index of suicidality was demonstrated to have some utility in the identification of suicide attempters and nonattempters. These findings add further weight of evidence to the suggestion that adolescents who enter the spectrum of suicide behaviours are at high risk of making a suicide attempt, although this requires further investigation in a prospective study.