The aims of this study were to investigate the degree of mental health problems among adolescents with immigrant background in Portugal and the factors that may predict mental health problems. The study sample consisted of 755 immigrant adolescents from seven ethnocultural groups (Cape Verdeans, Angolans, Indians, Mozambicans, East Timorese, Sao Tomese, and Guineans) and 320 native Portuguese adolescents. Generally, most respondents did not report major psychological adjustment problems. Adolescents from immigrant families reported fewer mental health problems than their native Portuguese counterparts, and girls reported more mental health problems than did boys. Predictive factors—sociodemographic, intercultural contact, and psychosocial adjustment variables—were significantly linked to youths' mental health. Major predictors of poor psychological adjustment were perceived discrimination, social difficulties, and behavioral problems. As expected, different factors explained the psychological adaptation of adolescents by gender. Implications of the study for counselors are discussed.