Before the developmental trajectory, outcomes, and related interventions of gratitude can be accurately and confidently studied among the youth, researchers must ensure that they have psychometrically sound measures of gratitude that are suitable for this population. Thus, considering that no known scales were specifically designed to measure gratitude in youth, this study aimed to answer an important question: Are the existing gratitude scales used with adults valid for use with youth? The present study is an empirical investigation, based on a large youth sample (N = 1,405) with ages ranging from 10 to 19 years old, of the psychometric properties of scores of the Gratitude Questionnaire-6 (GQ-6; M. E. McCullough, R. A. Emmons, & J.-A. Tsang, 2002), the Gratitude Adjective Checklist (GAC; M. E. McCullough, R. A. Emmons, & J.-A. Tsang, 2002), and the Gratitude Resentment and Appreciation Test (GRAT)-short form (M. Thomas & P. Watkins, 2003). Single-group and multiple-group confirmatory factor analyses indicated that the factor structures of these gratitude scales resemble those found with adults and were invariant across age groups. Scores of all three gratitude scales revealed acceptable internal consistency estimates (i.e., greater than 0.70) across age groups. Results showed that whereas scores of all three gratitude scales were positively correlated with each other for 14- to 19-year-olds, GRAT-short form scores tended to display relatively low correlations with scores of the other two measures for younger children (10-13 years old). Furthermore, the nomological network analysis showed that scores of all three gratitude scales were positively correlated with positive affect and life satisfaction scores across the age groups. The relationships with negative affect and depression scores, however, seemed dependent on the child's age. Pending results from subsequent research recommendations for researchers interested in studying gratitude in youth are offered. (Contains 6 tables and 1 footnote.)