OBJECTIVES: Existing evidence, mainly from high-income countries, shows children who witness intimate partner violence (IPV) at home are more likely to experience other forms of violence, but very little evidence is available from lower income countries. In this paper we aim to explore whether Ugandan children who witness IPV at home are also more likely to experience other forms of maltreatment, factors associated with witnessing and experiencing violence, and whether any increased risk comes from parents, or others outside the home. DESIGN: A representative cross-sectional survey of primary schools. PARTICIPANTS: 3427 non-boarding primary school students, aged about 11-14 years. SETTING: Luwero District, Uganda, 2012. MEASURES: Exposure to child maltreatment was measured using the International Society for the Prevention of Child Abuse and Neglect Child Abuse Screening Tool-Child Institutional, and 2 questions measured witnessing IPV. RESULTS: 26% of children reported witnessing IPV, but nearly all of these children had also experienced violence themselves. Only 0.6% of boys and 1.6% of girls had witnessed partner violence and not experienced violence. Increased risk of violence was from parents and also from other perpetrators besides parents. Both girls and boys who witnessed and experienced violence had between 1.66 (95% CI 0.96 to 2.87) and 4.50 (95% CI 1.78 to 11.33) times the odds of reporting mental health difficulties, and 3.23 (95% CI 1.99 to 5.24) and 8.12 (95% CI 5.15 to 12.80) times the odds of using physical or sexual violence themselves. CONCLUSIONS: In this sample, witnessing IPV almost never occurred in isolation-almost all children who witnessed partner violence also experienced violence themselves. Our results imply that children in Uganda who are exposed to multiple forms of violence may benefit from intervention to mitigate mental health consequences and reduce use of violence. IPV prevention interventions should be considered to reduce child maltreatment. Large numbers of children also experience maltreatment in homes with no partner violence, highlighting the need for interventions to prevent child maltreatment more broadly. TRIAL REGISTRATION NUMBER: NCT01678846, results.