The association of alcohol & drugs with suicidal thinking & behaviour is both causal & conducive. The subjective state of hopelessness is key to the disposition to actual suicide. Alcohol & drugs are influential in providing a feeling of hopelessness by their toxic effects & possibly by manipulating neurotransmitters responsible for mood & judgement. Because alcoholism & drug addiction are leading risk factors, any alcoholic or drug addict should be assessed for suicide potential. (27 refs.)