Purpose: Understanding why nearly 80% of youth ages 6-18 years with a mental disorder fail to receive treatment represents an important public health priority. International data suggest that underrecognition of mental illness and the need for treatment are barriers to service utilization. This study extends work to a U.S. sample of 1,104 adolescents. Methods: High School students were invited to participate in a self-report study assessing knowledge and beliefs regarding mental illness. Participants completed the survey in groups at school and read vignettes portraying peers experiencing major depression, social anxiety disorder, and a situation where the individual has to cope with a common life stressor followed by a series of questions in reference to each vignette. Results: Adolescents had better recognition of depression than social anxiety disorder and were more likely to recommend seeking help for it. However, <50% of youth recognized depression. Family, friends, and counselors were recommended as sources of help. Differences according to the sex of the respondent and person in the vignette were observed. Conclusions: These data are among the first to provide information regarding the mental health literacy of American adolescents and suggest potential points for intervention. Pending replication of the findings herein, efforts to help adolescents recognize mental health problems and to increase the likelihood of recommending professional help will be important.