This study examined (1) adolescent mental health literacy (MHL) and stigma for depression, anxiety and obsessive-compulsive and related disorders (OCRDs), and (2) demographic moderators. Participants were 383 high school students (50.9% boys) aged 11–18 years (M = 14.12, SD = 1.91) in El Salvador. Participants read vignettes of adolescents with mental health problems and reported on their beliefs about (1) what was wrong with the young person, (2) expected recovery time, (3) help-seeking beliefs and recommendations, and (4) stigma and preferred social distance associated with each condition. Results suggested that recognition of mental health conditions, especially anxiety disorders and OCRDs, was limited, although one third could recognize depression in a peer. Help-seeking attitudes were favorable. Adolescents were only somewhat willing to be affiliated with someone experiencing a mental health problem. Girls showed better MHL and lower stigma than boys. Stigma was lower among those with exposure to mental health problems.