Using the randomly selected subsample of 1,000 youth (472 boys, M age = 12.2 years, SD = 1.5; 528 girls, M age = 12.1 years, SD = 1.4) drawn by Dowling, Getsdottir, Anderson, von Eye, and Lerner (in press) from a Search Institute (1984) archival data set, Young Adolescents and Their Parents (YAP), this research employed structural equation modeling procedures to appraise the structural relations among second-order factors of religiosity, spirituality, and thriving. Three hierarchically related models were tested: The first model was a complete mediation model that involved a direct effect of spirituality on thriving and an indirect effect of spirituality on thriving, mediated by religiosity, the second model only consisted of the mediated effect, and the third model only consisted of the direct effects of spirituality on thriving and religiosity on thriving. Consistent with expectations, the complete mediation model provided reasonably good fit to the data and was significantly better than either of the alternative models. The importance of the findings reported here for the future study of youth thriving using either the YAP data set or new, longitudinal studies is discussed. (Contains 3 tables and 3 figures.)