This study investigated cross-cultural differences in adolescent sleep hygiene and sleep quality. Participants were 1348 students (655 males; 693 females) aged 12-17 years from public school systems in Rome, Italy (n = 776) and Southern Mississippi (n = 572). Participants completed the Adolescent Sleep-Wake Scale and the Adolescent Sleep Hygiene Scale. Reported sleep hygiene and sleep quality were significantly better for Italian than American adolescents. A moderate linear relationship was observed between sleep hygiene and sleep quality in both samples (Italians: R =.40; Americans: R =.46). Separate hierarchical multiple regression analyses showed that sleep hygiene accounted for significant variance in sleep quality, even after controlling for demographic and health variables (Italians: R-2 =.38; Americans: R-2 =.44). The results of this study suggest that there are cultural differences in sleep quality and sleep hygiene practices, and that sleep hygiene practices are importantly related to adolescent sleep quality