The purpose of this study was to evaluate the efficacy of a workplace parenting intervention aimed at reducing work–family conflict and improving work and family functioning in teachers. One hundred and seven teachers (who were also parents) were randomly allocated to either a Workplace Triple P intervention condition or a waitlist control condition. Analyses indicated the intervention had a positive effect on a range of occupational variables including work-to-family conflict, family-to-work conflict, occupational stress and teaching efficacy. Intervention effects were also found for family- and personal adjustment-related variables including dysfunctional parenting styles, child behaviour, parenting efficacy, and depression and anxiety. Small to large effect sizes were obtained (Cohen’s d = .34–.85), and all intervention effects were maintained at 4-month follow-up. The results indicate that a parenting intervention can reduce work–family conflict and occupational stress and improve family functioning in teachers balancing work and family. The implications for supporting teachers with family interventions delivered in the workplace are discussed.