Vaping rates among Canadian youth are significantly higher compared to adults. While it is acknowledged that various personal and socio-environmental factors influence the risk of school-aged youth for vaping uptake, we don't know which known behavior change factors are most influential, for whom, and how. The Unified Theory of Behavior (UTB) brings together theoretically-based behavior change factors that influence health risk decision making. We aimed to use this framework to study the factors that influence decision making around vaping among school-aged youth. Qualitative interviews were conducted with 25 youth aged 12 to 18 who were either vaped or didn't vape. We employed a collaborative and directed content analysis approach and the UTB constructs served as the coding framework for analysis. Gender differences were explored in the analysis. We found that multiple intersecting factors play a significant role in youth decision making to vape. Youth who vaped and those who did not vape reported similar mediating determinants that either reinforced or challenged their decision-making, such as easy access to vaping, constant exposure to vaping, and the temptation of flavors. Youth who didn't vape reported individual determinants that strengthened their intentions to not vape, including more negative behavioral beliefs (e.g., vaping is harmful) and normative beliefs (e.g., family disapproves), and strong self-efficacy (e.g. self-confidence). Youth who did vape, however, reported individual determinants that supported their intentions to vape, such as social identity, coolness, and peer endorsement. The findings revealed cohesion across multiple determinants, suggesting that consideration of multiple determinents when developing prevention messages would be beneficial for reaching youth.