- UNLABELLED: The negative effects of displacement and poverty on child mental health are well-known, yet research on prevention interventions in low- and middle-income countries, especially fragile states, remains limited. We examined the effectiveness of a parenting skills intervention on mental health outcomes among Burmese migrant and displaced children living in 20 communities in Thailand. Participants were primary caregivers and children aged 7 to 15 years (n = 479 families). Families were randomly assigned to receive an adapted version of the Strengthening Families Program (n = 240) or a wait-list control condition (n = 239). Assessments were conducted at baseline and 1-month post-intervention for both conditions and at 6 months for treatment group only. One month after the program, children in the treatment condition showed significant reductions in externalizing problems (caregiver effect size (ES) -0.22, p = 0.02; child report ES -0.11, p = 0.02) and child attention problems compared with controls (caregiver report ES -0.23, p = 0.03). There was no significant treatment effect on children's internalizing problems (ES -0.06; p = 0.31). Children reported a significant increase in prosocial protective factors relative to controls (ES 0.20, p < 0.01). Results suggest that an evidence-based parenting skills intervention adapted for a displaced and migrant Burmese population facing high levels of adversity can have positive effects on children's externalizing symptoms and protective psychosocial factors. TRIAL REGISTRATION: Clinicaltrials.gov: https://clinicaltrials.gov/show/NCT01829815.