Purpose: To determine the prevalence of possible tooth grinding (TG) and possible sleep bruxism (SB) and to examine their impacts on oral health–related quality of life (OHRQoL) among Asian adults. Materials and Methods: A total of 3,072 subjects (18 to 65 years of age) from 12 dental centers were invited to complete a self-administered questionnaire on TG/SB and OHRQoL, and 2,417 were included in the study. Participants were subsequently categorized into three groups (no TG/SB, possible TG, and possible SB) based on the International Classification of Sleep Disorders. The 14-item Oral Health Impact Profile (OHIP-14) severity, extent, and prevalence scores were subsequently computed and compared. Data were examined using Kruskal-Wallis and Mann-Whitney U tests, Spearman correlation, and univariate regression analysis (P .05). Results: Of the 2,417 subjects (mean age 24.79 ± 7.49 years), 42.82% reported either possible TG (n = 921; 38.11%) or possible SB (n = 114; 4.72%). Significant differences in global and domain OHIP-14 scores were found between the groups, except for the extent scores in functional limitation and physical disability. Mean global severity scores of the possible SB group (9.36 ± 9.45) were 1.5- and 2.2-fold larger than the possible TG (6.39 ± 7.61) and no TG/SB (4.22 ± 6.15) groups, respectively. A significant but weak correlation (r = 0.14 to 0.19) was found between the number of positive responses for TG/SB and OHIP-14 severity scores. Conclusions: A high prevalence of possible TG and SB was found among the Asian cohort studied. Possible TG and SB were significantly associated with poorer OHRQoL. The physical pain, psychologic discomfort, and psychologic disability domains were most influenced by TG/SB. More epidemiologic studies on the functional, physical, and psychosocial influences of SB are required.