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A) Pre-Intervention Measurement Instruments: - Initial Interview
Developed by Saucedo and Salazar in 2004 ( cited in Martínez et al., 2012 ), the initial interview is an instrument that allows obtaining information on various indicators, such as the pattern of substance use, history of use, willingness to change, social situation and family, leisure time management, sexuality, work situation, physical health and adverse consequences associated with the use of substances.
Ii. Problems In Adolescent Screening Questionnaire (Posit)
Developed by the authors Mariño, González-Forteza, Andrade, and Medina-Mora in 1997, the POSIT consists of 81 items that cover seven areas of operation; For this program, only the 17 items from the substance use/abuse area were used. The internal reliability of the instrument is .90, obtained through Cronbach’s α. The purpose of its application is the identification of adolescents who present at least one negative consequence associated with the consumption of psychoactive substances.
- B) Measurement Instruments Applied In Monitoring:
- Retrospective Baseline (LIBARE)
Developed by Sobell and Sobell in 1979, the LIBARE is used to measure the pattern of substance use (amount and frequency) before, during, and after treatment; With it, three months of consumption are measured at the beginning of the treatment. It
Ii. Situational Confidence Questionnaire Short Form (Ccs)
This instrument was developed by Annis and Davis (1988), who was based on Bandura’s concept of self-efficacy. Users are asked to indicate, on a scale from 0 to 100%, how confident or secure they feel at the present moment to resist the temptation to use a drug in the imaginary situation that arises. The summary of the Situational Confidence Questionnaire consisting of eight items ( Echeverría & Ayala, 1997 ) was used; In this version adapted to the Mexican population, the validity of the construct was adequate when correlating each category with measures of consumption, which made it possible to predict relapse situations.
Iii. Follow-Up Interview
This instrument aims to identify the adolescent’s progress in achieving his goal after the intervention has concluded. The follow-up interview that was used for this research was developed at the CPAHAV, based on the efficacy indicators of brief interventions ( Echeverría & Ayala, 1997 ) and includes the main characteristics that should be evaluated in a follow-up ( Hester & Miller, 1989 ). This research measured the following dimensions: consumption pattern and adverse consequences associated with consumption.
- C) Measurement Instruments Applied In Monitoring:
- Collateral Interview
This instrument is complementary to the follow-up interview. It is useful to contrast the information provided by the adolescent with that reported by one of her relatives; It investigates the amount and frequency of the user’s substance use, as well as their relationship and the frequency of meeting the adolescent with her collaterals.
Ii. Informed Consent
Informed consent is a document the user signs if they agree to participate in the research. He 
explains that the follow-up is intended to support the change process after the intervention, and it discloses the confidentiality of the data reported by the user.
Ethical Considerations
In this study, the activities for data collection complied with the guidelines established by the Psychologist’s Code of Ethics and the American Cognitive Association. The candidates signed an informed consent form in which the characteristics of the intervention are described, the confidential nature of the information is indicated, and the signatories are given the freedom to abandon the treatment at any time they wish without this having an impact on their rights and obligations; The participants, for their part, grant those who carry out the study the possibility of using the data collected for research purposes. The parents or guardians also signed the consent form if the participants were minors.