BACKGROUND: Violence against children from school staff is anecdotally common in low- and middle-income countries, but data on prevalence and associations with mental health and educational outcomes are lacking. METHODS: We report data from a cross-sectional survey conducted in June and July 2012 in Luwero District, Uganda. Forty-two primary schools representing 80% of students in the district were randomly selected; 100% agreed to participate. The International Society for the Prevention of Child Abuse and Neglect Child Abuse Screening Tool-Child Institutional; Strengths and Difficulties Questionnaire; and reading, spelling, and math tests were administered. We present descriptive statistics and logistic regression models, accounting for the complex sampling scheme used in the survey. RESULTS: We surveyed 3706 students and 577 school staff members; 93.3% (SE 1.0%) of boys and 94.2% (SE 1.6%) of girls attending primary school reported lifetime experience of physical violence from a school staff member, and >50% reported experience in the past week. Past-week physical violence was associated with increased odds of poor mental health and, for girls, double the odds of poor educational performance (adjusted odds ratio = 1.78, 95% confidence interval = 1.19-2.66). For boys, significant interactions were present. CONCLUSIONS: Despite a ban on corporal punishment in Ugandan schools since 1997, the use of violence against students is widespread and associated with poor mental health and educational performance. School violence may be an important but overlooked contributor to disease burden and poor educational performance in low- and middle-income settings.