This observational study evaluates the psychometric properties of the Behavioral Activation for Depression Scale (BADS) in individuals with substance use disorders. The study examines the scale's internal structure, reliability, and validity using data from 289 participants who completed the BADS. External and incremental validity analyses were conducted in a subsample of 127 participants for whom additional clinical measures were available, including assessments of symptom severity, anxiety, impulsivity, and anger expression. This approach reflects the availability of complete data for each analytic component and allows for a comprehensive evaluation of the BADS in a clinical population.

This study employs a cross-sectional observational design to evaluate the psychometric performance of the Behavioral Activation for Depression Scale (BADS) in individuals with substance use disorders. The validation process consisted of two complementary analytic components based on data availability.

First, analyses of internal structure, reliability, and item-level performance were conducted using data from 289 participants who completed the BADS. These analyses included advanced psychometric methods to evaluate the dimensional structure and measurement properties of the scale.

Second, external and incremental validity analyses were conducted in a subsample of 127 participants for whom complete data were available on additional validated self-report measures assessing clinically relevant constructs, including symptom severity, anxiety, impulsivity, and anger expression. This subsample approach reflects the naturalistic data collection process in clinical settings and allowed for the examination of the BADS' relationships with external criteria without imputing missing data.

Together, these analyses provide a comprehensive evaluation of the BADS, integrating evidence from internal psychometric validation and external criterion-related validity in a clinical population with substance use disorders.

Inclusion Criteria:

• Adults aged 18 years or older.
• Currently receiving treatment or undergoing clinical evaluation for substance use disorders in a therapeutic or clinical setting.
• Ability to read and understand Spanish.
• Ability to provide informed consent.
• Completion of the Behavioral Activation for Depression Scale and at least one additional study questionnaire.

Exclusion Criteria:

• Severe cognitive impairment or acute psychiatric symptoms that prevent accurate self-reporting.
• Incomplete or missing data on key study measures.
• Current intoxication or acute withdrawal symptoms at the time of assessment that interfere with completing questionnaires.

The study population consists of adults receiving residential treatment for substance use disorders in a therapeutic community setting. Participants represent a clinically relevant population characterized by difficulties in mood regulation, behavioral activation, emotional dysregulation, and related psychological symptoms commonly associated with substance use disorders.