The aim of the study was to evaluate the psychometric properties of the Turkish version of the Acceptance and Action Questionnaire-II (AAQ-II). This instrument was designed to assess psychological inflexibility, a key construct in Acceptance and Commitment Therapy (ACT). The participants were 291 university students. The test-retest stage was conducted with 80 participants over a 2-month period. Confirmatory Factor Analysis (CFA) supported a one-factor model with seven items. Internal consistency was high (.88) and test-retest reliability was good (.78). Higher AAQ-II scores were associated with higher levels of depression, anxiety, and thought suppression supporting the concurrent and convergent validity. This study provides further evidence of the improvement shown by the 7-item version of the AAQ-II in terms of psychometric properties compared with the previous versions. Our results suggest that the Turkish version of the AAQ-II is a reliable and valid measure of psychological inflexibility.