Factors associated with suicidal ideation and attempts were examined among a national probability sample of adolescents. Sample prevalences of suicidal ideation and attempts were 24.3% and 3.3%, respectively, yielding weighted population prevalence estimates of 23.3% and 3.1%. Suicidal ideation was positively associated with female gender, age, family alcohol and drug problems, violence exposure, lifetime depression, and posttraumatic stress disorder (PTSD). Suicide attempts were associated with female gender, age, sexual and physical assault, lifetime substance abuse or dependence, PTSD, and depression. Implications for intervention and prevention are discussed.