The current study evaluated the reliability and validity of psychological flexibility self-report measures between typically developing under 18 and over 18 aged individuals. An independent samples t test with a correlational statistical analysis was conducted to evaluate the relationship between the CPFQ, CAMM, AFQY and AAQII. The results demonstrated that three out of four measures are reliable and valid in determining psychological flexibility between the two groups. This study adds to literature that is conducive in the analysis of measures that are designed for younger population to be utilized by practitioners with older populations reliably.