Exploring the Validity of Adolescent Responses to a Measure of Psychological Flexibility and Inflexibility

Validating measures of psychological flexibility (PF) and psychological inflexibility (PI) has occurred in multiple adult samples, but little research has validated PF and PI measures with adolescents. This manuscript describes two studies exploring the validity of responses to the Multidimensional Psychological Flexibility Inventory (MPFI) with two samples of adolescents. The first study used exploratory factor analyses on responses to the MPFI with a sample of 16-17-year-olds (<i>N</i> = 249). The results yielded a reduced and simplified measurement model that consisted of two general factors: one for PF and the other for PI. These exploratory findings were further investigated with confirmatory factor analyses in the second study, with a larger sample of 14-17-year-olds (<i>N</i> = 503). The results from the second study generally confirmed the factor model from the first study. Findings from both studies showed that scores derived from the reduced MPFI measurement model evidenced convergent and divergent validity with a variety of mental health criterion measures. Moreover, findings from the second study showed that PF and PI scores had differential predictive power on different concurrent mental health outcomes. This discussion highlights the implications of measuring PF and PI in adolescents, considers limitations of the present studies, and recommends next steps for research.