Religiousness exerts a protective effect against underage alcohol use, but it is largely unknown whether its protective quality extends equally to alcohol-related problems. It is also unclear to what extent spirituality, which is related to religiousness, exerts a similar protective effect. The current study examined whether facets of religiousness and spirituality - religious commitment and spiritual transcendence - were differentially related to alcohol use and alcohol-related problems among an underage sample of young adults. Despite being underage, most participants (n = 344; 61 female) reported having an alcoholic drink at least once a month and having at least two to three drinks per occasion. Results of hierarchical linear regression analyses that controlled for demographics, positive alcohol expectancies, and impulsivity found unique associations between religious commitment and spiritual transcendence and alcohol use. Specifically, religious commitment operated as a protective factor, while spiritual transcendence operated as a risk factor for alcohol use. Neither religious commitment nor spiritual transcendence predicted alcohol-related problems. Results of this study inform future research by highlighting the importance of studying religiousness and spirituality as unique constructs with the potential for differential predictive utility.