Does the order of substance initiation predict future substance use? The Gateway Theory proposes that tobacco or alcohol use can lead to marijuana use, which itself can lead to initiation of other illicit drugs. However, other research suggests no significant association between substance initiation sequence and substance use disorder (SUD). In an effort to further investigate this issue, a recent study explored the relationship between initiation sequence and current substance use and SUD among the general French population. The authors conducted a retrospective analysis of data collected in 2010 from individuals aged 15-85 years old through a telephonic survey. In this survey, participants self-reported past year substance use as well as their age of substance use initiation (n=22,774). Although seven substance initiation sequences were observed, the most prevalent sequences included initiation of tobacco only (45.5%), tobacco followed by cannabis (20.5%), cannabis followed by tobacco (5.1%), and lastly, initiation of tobacco, then cannabis, then other illicit drugs (3.5%). Statistical analyses revealed that the risk of substance use and SUD increased with the number of substances previously initiated, which agrees with earlier published reports. In addition, further statistical analyses demonstrated that the risk is the same regardless of the sequence of initiation. Take Away: This study suggests that polysubstance initiation may serve as a better predictor of future substance use than sequence initiation, suggesting theories that account for genetic and individual vulnerabilities may better explain the relationship between substance initiation and future substance use.