The objective of this study is to assess the efficacy of an intervention designed to promote resilience in young children living with their HIV-positive mothers.HIV-positive women attending clinics in Tshwane, South Africa, and their children, aged 6-10 years, were randomized to the intervention (I) or standard care (S). The intervention consisted of 24 weekly group sessions led by community care workers. Mothers and children were in separate groups for 14 sessions, followed by 10 interactive sessions. The primary focus was on parent-child communication and parenting. Assessments were completed by mothers and children at baseline and 6, 12 and 18 months. Repeated mixed linear analyses were used to assess change over time.Of 390 mother-child pairs, 84.6% (I: 161 and S: 169) completed at least two interviews and were included in the analyses. Children's mean age was 8.4 years and 42% of mothers had been ill in the prior 3 months. Attendance in groups was variable: only 45.7% attended more than 16 sessions. Intervention mothers reported significant improvements in children's externalizing behaviours (ß = -2.8, P = 0.002), communication (ß = 4.3, P = 0.025) and daily living skills (ß = 5.9, P = 0.024), although improvement in internalizing behaviours and socialization was not significant (P = 0.061 and 0.052, respectively). Intervention children reported a temporary increase in anxiety but did not report differences in depression or emotional intelligence.This is the first study demonstrating benefits of an intervention designed to promote resilience among young children of HIV-positive mothers. The intervention was specifically designed for an African context and has the potential to benefit large numbers of children, if it can be widely implemented.