The Swiss Youth Mental Health Literacy and Stigma Survey (SYMHLSS) aimed to study mental health literacy and stigma towards mentally ill people in a representative youth sample. The survey has been adapted from the Australian National Survey of Youth Mental Health Literacy and Stigma. As in the Australian survey, vignettes describing a person with a mental disorder were the core element to which most subsequent survey questions referred. Five vignettes were used in the online-based Swiss survey: 1) depression; 2) alcohol abuse; 3) depression and alcohol abuse combined; 4) schizophrenia, and 5) social anxiety disorder. A representative school-based sample of roughly 5000 students at the upper secondary educational level (voccational schools, high schools) filled out the online questionnaire.