An estimated 877,000 lives were lost through suicide worldwide in 2002. In the United States, in 2003, more than 31,000 individuals died by suicide, making it the 11th leading cause of death. Men are four times more likely than women to die by suicide, however women make more nonfatal suicide attempts than men. There are many contributory factors to suicide and suicide attempts, the most important of which is having psychiatric disorder. More than 90% of suicides have a diagnosable psychiatric disorder at the time of their death, the most common being mood disorders. Other disorders with increased risk for suicidal behavior are psychotic disorders, alcohol and substance use disorders, and personality disorders, particularly Cluster B personality disorders. Other risk factors for suicide and suicide attempt include a family history of suicide and suicide attempt, a history of previous suicidal behavior, aggressive/impulsive traits, hopelessness and pessimism, a history of childhood abuse, head injury, and access to lethal means such as firearms. Assessing a suicidal patient involves evaluating current stressors as well as assessing enduring risk factors and indicators that an individual has a propensity to engage in suicidal behavior when under stress. Stressors include current life events or an episode of psychiatric illness, particularly a depressive episode. Longer-term risk factors include aggressive and impulsive traits, trait pessimism, and a history of past suicidal behavior because it indicates a predisposition to suicidal acts. Individuals who present with severe suicidal ideation, a definite plan for suicide, and who have ready access to lethal means are at high risk and require immediate intervention, up to and including hospitalization. Long-term treatment strategies should also include addressing enduring risk factors.