The association of alcohol and drugs with suicidal thinking and behavior is both causal and conductive. The subjective state of hopelessness is key to the disposition to actual suicides. Alcohol and drugs are influential in providing a feeling of hopelessness by their toxic effects, by possible manipulating of neurotransmitters responsible for the mood and judgement and by disruption of interpersonal relationships and social supports. The identification of alcohol and drug use and dependence is critical to the proper assessment of suicide. According to studies, over fifty percent of all suicides are associated with alcohol and drug dependence and at least 25% of alcoholics and drug addicts commit suicide. Over 70% of adolescent suicides may be complicated by drug and alcohol use and dependence. Because alcoholism and drug addiction are leading risk factors for suicidal behavior and suicide, any alcoholic or drug addict should be assessed for suicide, especially if actively using alcohol or drugs.