Findings indicated more than one third of ideators reported a plan, about one fourth reported an attempt, and more than half of those with a suicide plan made an attempt. Risk of suicide ideation, plan, and attempt began increasing at age 10, and peaking around age 15. Females were found to have the highest risk of ideation, plan, and attempt. Among ideators, suicide attempt was also related to having a plan and was most likely to start within the first year of developing an ideation and a plan. Having met criteria for one or more DSM-IV disorders was a strong predictor of suicidality. The number of lifetime disorders was an especially strong predictor of suicidality in the total sample. Among ideators, only dysthymia was consistently related to a plan and an attempt. Mexico had one of the largest increases in suicide between 1990 and 2000 among 28 countries examined, experiencing a large migration to urban areas and profound social changes, including diminished extended family ties in favor of more nuclear ones and increases in divorce, job insecurity, and income loss. Despite this context of rapid social change and new forms of social relationships, Mexico remains a Catholic country and suicide in all forms is regarded as a sin and shame for the family. Few programs for prevention and treatment exist. Suicide and nonlethal suicidal thoughts and behaviors are an important component of the current epidemiological profile of adolescents in Mexico; detection of those with suicide ideation, suicide plan, and mental disorders are important measures to be taken because they are important risk factors that lead to attempts. Data were collected from the 2005 Mexican Adolescent Mental Health Survey, a representative household survey of 3,005 adolescents ages 12 to 17 in metropolitan Mexico City. Tables, figures, references