Validation of the Italian Multidimensional Psychological Flexibility Inventory Short Form (MPFI-24)

This research examines the psychometric properties of the Italian Multidimensional Psychological Flexibility Inventory short form (MPFI-24), a measure of psychological flexibility/inflexibility. Study 1 investigated its factor structure, reliability and invariance (across gender, age, and mental health status) based on a dataset comprising 1542 participants (71% female, meanage = 38.6 years, SD = 15.0). Study 2 reexamined the factorial structure in an independent sample (N = 728, 64.88% females, meanage = 30.94 years, SD = 14.07), and assessed both convergent validity (with psychological flexibility/inflexibility measures) and concurrent validity (with distress and well-being measures). Confirmatory factor analyses demonstrated very good fit indices for a first-order model comprising the twelve psychological flexibility and inflexibility sub-processes. In addition, the model structured with two second-order factors—psychological flexibility and inflexibility—each defined by six core sub-processes, showed a good model fit. The Italian MPFI-24 also exhibited strong internal consistency and good convergent and concurrent validity. Measurement invariance was established for gender, age, and mental health status. The Italian MPFI-24 is a psychometrically sound instrument for evaluating psychological flexibility and inflexibility, along with their underlying sub-processes, in an Italian context.