BACKGROUND: Vaping among adolescents and young adults is a significant public health concern worldwide. Understanding which risk factors are associated with vaping is important to help inform evidence-based prevention and intervention strategies. There are several gaps in the current literature examining these associations such as limited longitudinal research. We examined the association between parental smoking/vaping, adolescent sex, mental disorders in adolescence, 13 adverse childhood experiences (ACEs) and a) any vaping and b) course of vaping across two time points among adolescents and young adults. METHODS: Data were from Waves 1 and 2 of the longitudinal Well-Being and Experiences Study (The WE Study) in Manitoba, Canada which collected data from a community sample of adolescents (14 to 17 years) and their parent/caregiver in Wave 1 in 2017-18 and the adolescents/young adults only in Wave 2 in 2019. A total of 752 adolescents/young adults (72.4% of the original cohort) completed both waves of the study. Binary and multinomial logistic regressions were conducted to understand the relationship between the 16 risk factors and the two vaping outcomes. RESULTS: Vaping prevalence was 45.5% for any vaping, 2.7% for Wave 1 vaping only, 19.7% for new onset Wave 2 vaping, and 21.2% for vaping at both waves. After adjusting for covariates, the majority of risk factors examined were associated with any adolescent or young adult vaping, including: parental smoking or vaping, emotional abuse, emotional neglect, exposure to verbal intimate partner violence, household substance use, household mental illness, parental separation/divorce, parental problems with police, foster care or contact with a child protective organization, an unsafe neighbourhood, and peer victimization. The majority of these risk factors, as well as adolescent mental health and parental gambling, were associated with different courses of vaping across the two time points. CONCLUSIONS: The findings emphasize the need for early vaping prevention and identified several ACEs and other factors that were associated with adolescent and young adult vaping and course of vaping. These identified ACEs and risk factors can help inform programs, strategies, and potential groups to target for vaping interventions.