The gateway theory hypothesizes that the use of legal drugs such as tobacco may lead to cannabis consumption. This study sought to determine the prevalence of Swiss youth who use cannabis but have never been tobacco smokers and to assess how they differ from youth using both substances. Six percent of youth were current cannabis users, 21% of whom had never used tobacco. Compared with those using both substances, youth using only cannabis were younger, more likely to be male, played sports, and did well in school. They were less likely to report having been drunk, started cannabis use at a later age, and had less overall use. However, the path between being an occasional vs regular user of cannabis is not well established, and this group of adolescents needs to be monitored over time.