The contribution of a series of measures of personality and/or cognitive style to serious suicide attempt risk in young people was examined in a case-control study. Individuals making suicide attempts had elevated odds of hopelessness, neuroticism, introversion, low self-esteem, impulsiveness, and external locus of control. When allowance was made for intercorrelations between these measures, hopelessness, neuroticism, and external locus of control remained significant risk factors for serious suicide attempt; self-esteem, extraversion, and impulsiveness were not significantly associated with suicide attempt risk. Nonsignificant findings were explained by the presence of substantial correlations between these measures and measures of hopelessness, neuroticism, and external locus of control.