Cannabis smokers who also smoke tobacco cigarettes have markedly higher rates of cannabis
relapse relative to those who do not use tobacco. There is a clear need to develop and
evaluate interventions for dual tobacco and cannabis users. The investigators of this study
have previously shown that the co-use of tobacco cigarettes contributes to the maintenance of
daily cannabis use, and that age of cigarette onset is a critical predictor of treatment
outcome. Short-term tobacco cessation may suffice in altering cannabis relapse rates in
later-onset cigarette smokers, while a longer period of tobacco cessation may be needed for
earlier-onset smokers. In the current study, a human laboratory model will be utilized to
determine whether cannabis relapse varies as a function of tobacco cessation duration and age
of tobacco use onset.