The present research project aims to develop an innovative and empirically validated intervention protocol for smoking cessation among patients with substance use disorders (SUDs). For this purpose, two smoking cessation treatments tailored for SUDs will be assessed. Participants will be assigned to one of the following treatment conditions: 1) Cognitive-behavioral treatment for smoking cessation (CBT) + Episodic Future Thinking (EFT); 2) The same treatment alongside Contingency Management (CM) for shaping abstinence.

The main goals are:

1. To analyze the feasibility (e.g., acceptability, compliance) of implementing the abovementioned protocol treatments to a community setting.
2. To assess abstinence rates in each treatment condition at short and long-term follow-ups: post-treatment, one, two, three, six and twelve months after post-treatment.
3. To assess the effects of smoking abstinence on other substance use.
4. To analyze the moderating effect of individual variables over treatment outcomes: sociodemographic characteristics, drug demand, severity of nicotine dependence and SUD, severity of depressive symptomatology and impulsivity.

Cigarette smoking continues to have a startling adverse impact on public health, leading to more than 5 million premature deaths annually worldwide. Smoking rates are disproportionately high among the population suffering from substance use disorders (SUDs) (e.g., alcohol or cocaine). In this regard, smokers with comorbid SUD are more likely to smoke heavily and meet criteria for high nicotine dependence. As they experience more difficulty in quitting smoking than their non-SUDs counterparts, they present lower rates of abstinence.

In recent years there has been a great interest in developing effective strategies to promote abstinence in smokers with SUDs. In particular, a proliferation on CM treatments for smokers with SUDs has been recently produced. There is promising evidence for the positive effect of CM treatments upon both quitting smoking and both legal and illegal abuse drugs. On the other hand, CM has shown promising results in promoting both retention and nicotine abstinence among comorbid and non-comorbid smokers. Nevertheless, there is a lack of research exploring the effectiveness of CM on smokers with SUDs.

The primary aim of this clinical trial is to yield data on the effectiveness of CM for smoking cessation in smokers with SUDs. To address this issue, both CBT for smoking cessation plus EFT, and the same treatment alongside CM for shaping abstinence will be assessed. Participants will be randomly assigned to one of the following treatment conditions: 1) CBT+EFT; 2) CBT+EFT+ CM.

In view to assure adequate power for achieving statistical significance, investigators carried out a priori power analysis by using the G*Power 3.1. An estimated sample size of 120 participants would detect a medium effect size (Cohen's d = 0.3, with power (1-β) set at 0.97 and α = 05).

The primary analyses derived from this clinical trial will be conducted using Statistical Package for the Social Science (SPSS) version 24 for Windows. A set of descriptive and frequency analyses will be carried out with regard to participants' characteristics. Comparisons between treatment groups in both baseline characteristics and treatment outcomes will be conducted using a set of chi-square tests for categorical variables and t-tests (two-tailed) for continuous variables.

Inclusion Criteria:

• Being aged 18 or over.
• Having smoked 10 or more cigarettes/day within the last year.
• Meeting the diagnostic criteria for nicotine dependence according to the Diagnostic and Statistical Manual of Mental Disorders-5th ed. (American Psychiatric Association 2013).
• Undergoing outpatient cocaine or alcohol treatment.

Exclusion Criteria:

• Not being able to attend the entire treatment.
• Being currently receiving other psychological/pharmacological treatment for smoking cessation.
• Being diagnosed with a current severe psychiatric disorder (i.e., schizophrenia,bipolar disorder).