Suicidal trends and related characteristics such as sociodemographic factors, psychological factors, and health behaviors can differ between countries. This study investigated the predictors of suicidal ideation and attempted suicide including health behaviors among American and Korean youth from two national representative data sets. In both countries, depression was the most predominant predictor to suicidal ideation and attempted suicide. Unique predictors of suicidal youth in each country were also found. In America, attempted suicide was predicted by poor body image, whereas in Korea attempted suicide was predicted by medical diagnosis such as asthma, concern about weight, and alcohol consumption. The value of our approach lies in the comparative analysis of analogous and unique characteristics of suicidal youths in these two huge data sets from different countries. These results should be helpful for school and mental health care providers to plan interventions for youth at risk of suicide to prevent suicidal completion in these nations. (Contains 5 tables.)