ABSTRACT: BACKGROUND:Parenting programs suitable for delivery at scale in low-resource contexts are urgently needed. We conducted a randomized trial of Parenting for Lifelong Health (PLH) for Young Children, a low-cost 12-session program designed to increase positive parenting and reduce harsh parenting and conduct problems in children aged 2-9. METHODS:Two hundred and ninety-six caregivers, whose children showed clinical levels of conduct problems (Eyberg Child Behavior Inventory Problem Score, >15), were randomly assigned using a 1:1 ratio to intervention or control groups. At t0 , and at 4-5 months (t1 ) and 17 months (t2 ) after randomization, research assistants blind to group assignment assessed (through caregiver self-report and structured observation) 11 primary outcomes: positive parenting, harsh parenting, and child behavior; four secondary outcomes: parenting stress, caregiver depression, poor monitoring/supervision, and social support. TRIAL REGISTRATION:ClinicalTrials.gov (NCT02165371); Pan African Clinical Trial Registry (PACTR201402000755243); Violence Prevention Trials Register (http://www.preventviolence.info/Trials?ID=24). RESULTS:Caregivers attended on average 8.4 sessions. After adjustment for 30 comparisons, strongest results were as follows: at t1 , frequency of self-reported positive parenting strategies (10% higher in the intervention group, p = .003), observed positive parenting (39% higher in the intervention group, p = .003), and observed positive child behavior (11% higher in the intervention group, p = .003); at t2, both observed positive parenting and observed positive child behavior were higher in the intervention group (24%, p = .003; and 17%, p = .003, respectively). Results with p-values < .05 prior to adjustment were as follows: At t1 , the intervention group self-reported 11% fewer child problem behaviors, 20% fewer problems with implementing positive parenting strategies, and less physical and psychological discipline (28% and 14% less, respectively). There were indications that caregivers reported 20% less depression but 7% more parenting stress at t1 . Group differences were nonsignificant for observed negative child behavior, and caregiver-reported child behavior, poor monitoring or supervision, and caregiver social support. CONCLUSIONS:PLH for Young Children shows promise for increasing positive parenting and reducing harsh parenting.