Purpose: The purpose of this study was to determine the association among stress levels, personality traits, and sleep bruxism in children. Methods: A population-based case control study (proportion=1:2) was conducted involving 120 7- to 11-year-olds with sleep bruxism and 240 children without sleep bruxism. The sample was randomly selected from schools in Belo Horizonte, Minas Gerais, Brazil. The following instruments were used for data collection: questionnaire administered to parents; child stress scale; and neuroticism and responsibility scales of the big five questionnaire for children. Psychological tests were administered and evaluated by psychologists. Sleep bruxism was diagnosed from parents' reports. The chi-square test, as well as binary and multivariate logistic regression, was applied for statistical analysis. Results: In the adjusted logistic model, children with a high level of stress, due to psychological reactions (odds ratio=1.8; confidence interval=1.1-2.9) and a high sense of responsibility (OR=1.6; Ci=1.0-2.5) vs those with low levels of these psychological traits, presented a nearly 2-fold greater chance of exhibiting the habit of sleep bruxism. Conclusion: High levels of stress and responsibility are key factors in the development of sleep bruxism among children.