AIMS: While laws restrict alcohol access to youth under the age of 16/18 (fermented/distilled beverages) in Switzerland, direct underage accessibility is high. Focusing on underage youth, our study presents an inventory of primary and alternative modes of access to alcohol and investigates associations with youth characteristics. METHODS: Data were collected using semi-structured interviews and self-report questionnaires. In total, 223 underage youth aged 15-17 years were interviewed. RESULTS: Overall, about half of the participants reported illegal commercial purchase, either direct or by underage peer, in on- (49.3%) and/or off-premise (48.0%) contexts. Off-premise purchase by proxy of legal age (30.5%; excluding shoulder-tapping), social supply off-premise (i.e. receiving/exchanging alcohol; 26.5%) and direct purchases in on- (13.9%) and off-premise (11.2%) contexts were the most recurrent primary modes of access. Significant associations of direct purchases with frequency of consumption and perceived alcohol availability were recorded. Associations between primary and alternative ways to access alcohol, in particular, between on-premise modes, were also evidenced. CONCLUSION: Providing an overview of the context of underage alcohol access in Switzerland and an indirect view of youth perceptions of limitations of existing structural measures has identified particularly the need for enforcement of existing legislation.