The current investigation aimed to test the relationship between religiousness and self-esteem. Religiousness was measured comprehensively by four indices (i.e., religious participation, positive religious coping, fundamentalism, optimistic afterlife beliefs). In addition, the study examined the key question of whether the relationships between the different indices of religiousness and self-esteem persist after controlling for the potential confounding variable dispositional optimism. The study utilized a cross-sectional design and a sample of Israeli adults (N = 451) from diverse ethnic and religious backgrounds. The findings revealed weak positive zero-order correlations between all indices of religiousness and self-esteem. However, none of these indices remained predictive of self-esteem when they were entered into the regression model alongside dispositional optimism. This was true both for the sample as a whole, and for Muslim and Jewish individuals, as well as secular, traditional, and religious individuals, separately. Furthermore, dispositional optimism fully mediated the links between all religious indices and self-esteem. The findings suggest that, at least in the specific sociocultural context in which this research was conducted, religiousness does not add a unique variance in predicting self-esteem, and its link to self-esteem can be explained by nonreligious variables.