Aims: To identify the predictors associated with smoking cessation in smokers under treatment for alcohol and/or cannabis treated in drug treatment centers (DTC). Methodology: Mixed methods project with qualitative and quantitative designs (three studies). Study I discussion groups: of clinical professionals of DTC to explore the barriers/facilitators of these smokers in quitting and the interventions carried out. Study II Prospective cohort of smokers in alcohol and/or cannabis treatment that will be followed-up for 12 months. Sample size: difference in incidence (exposed to cessation interventions versus non-exposed = 12 per 100 years), α = 0.05, β = 0.10, losses = 20% (n = 726). Dependent variables: self-reported and verified tobacco consumption abstinence, quit attempts, motivation, and self-efficacy. Independent variables: age, sex, the substance under treatment. Analysis: incidence, relative risk and simple and multiple logistic regression models (odds ratio and confidence interval, CI, 95%) of quitting. Study III discussion groups: with smokers under alcohol and/or cannabis treatment selected according to their typology. Analysis: of thematic content and triangulation qualitative and quantitative results. Expected results: Characterization of variables that influence tobacco cessation, to improve the design of interventions.

Inclusion Criteria:

• Smokers (at least 1cig./week)
• Undertreatment for Cannabis and/or Alcohol Abuse for the first time
• >=18 years-old
• Under clinical follow-up
• Informed consent

Exclusion Criteria:

• Severe cognitive impairment
• 12-month follow-up not guaranteed

Smokers under treatment for substance abuse (alcohol and/or cannabis) from the province of Barcelona in Catalonia (Spain)