Abstract
Evaluating psychological flexibility is key in determining the mechanism of action of an ACT intervention. This study aims to evaluate the psychometric properties of the Spanish version of the Acceptance and Action Questionnaire - Substance Abuse (AAQ-SA), a measure of psychological flexibility, among 402 adults with Substance Use Disorders (SUDs) in Puerto Rico recruited from either a prison population or community treatment settings. To evaluate the factor structure of the AAQ-SA, we conducted confirmatory factor analyses with the two-factor structure proposed by the original authors and the three-factor structure found in a Mexican sample. We found the two-factor structure to be a better fit of the data from our sample. After implementing modifications to the model, the two-factor structure demonstrated adequate model fit indices. To gather evidence of convergent validity, we evaluated correlations between scores of the AAQ-SA and those of depression, self-efficacy, and self-stigma measures. The current study suggests that the AAQ-SA is a promising measure of psychological flexibility for the present target populations. Further research is needed to examine the psychometric properties of scores of the AAQ-SA, including discriminant validity.