The roles of self-efficacy and self-monitoring as proximal predictors of dental flossing frequency are studied in the context of an oral health intervention. A study among 287 university students, aged 19 to 26 years, compared an intervention group that received a brief self-regulatory treatment, with a passive and an active control group. Dental flossing, self-efficacy, and self-monitoring were assessed at baseline and 3 weeks later. The intervention led to an increase in dental flossing regardless of experimental condition. However, treatment-specific gains were documented for self-efficacy and self-monitoring. Moreover, changes in the latter two served as mediators in a path model, linking the intervention with subsequent dental flossing and yielding significant indirect effects. Self-efficacy and self-monitoring play a mediating role in facilitating dental flossing. Interventions that aim at an improvement in oral self-care should consider using these constructs. Statement of contribution What is already known on this subject? The adoption and maintenance of oral self-care can be facilitated by a number of social-cognitive variables. Interventions that include planning, action control, or self-efficacy components have been shown to improve dental flossing. In one recent study on flossing in adolescent girls, planning intervention effects were mediated by self-efficacy. What does this study add? Self-monitoring is associated with better oral self-care. A 10-min intervention improves self-efficacy and self-monitoring. Self-efficacy and self-monitoring operate as mediators between treatment and flossing.