The development of gratitude in youth has received increasing attention during the past several years, and gratitude-based interventions have often been recommended for use in schools. Yet, the empirical status of the correlates of gratitude and the effects of gratitude-based interventions on youths' outcomes remains unclear. The present study addressed this ambiguity by systematically reviewing and meta-analyzing original empirical journal articles investigating gratitude in youth through September 2014 (N = 20). Findings from the meta-analysis of correlates indicate small-to-moderate convergent and discriminant evidence for gratitude as a subjective well-being indicator in youth, yet other results indicate that gratitude measures have relatively poor test--retest reliability and/or predictive validity and that they have questionable concurrent validity with other gratitude measures. Moreover, findings from the meta-analysis of intervention outcomes indicate that gratitude-based interventions are, as a whole, generally ineffective and that much more intervention research is warranted. Implications of these findings for theory, future research, and the practice of school psychology are discussed.