The Families First parenting program is a 10-week paraprofessional-administered adaptation of the Positive Discipline in Everyday Parenting program for West Java, Indonesia. It has not been tested in a randomized controlled trial. The objective was to evaluate the effects of Families First on physical and emotional punishment. We conducted a cluster randomized controlled trial and randomly assigned 20 rural and urban villages in West Java, Indonesia, to intervention or waitlist. Caregivers of children aged 0–7 years in intervention villages received Families First. Between 2017 and 2018, measurements were taken before randomization, immediately post-intervention, and 6 months post-intervention. Primary outcome was presence versus absence of caregiver-reported physical or emotional punishment immediately post-intervention. Intention-to-treat regression models accounted for clustering within villages and were run to compare between groups. Participants and study personnel could not be blinded. There were 374 caregivers in the 10 intervention villages and 362 in the 10 waitlist villages included in the trial and in outcome analyses. The intervention did not result in a lower proportion of intervention families using punishment immediately post-intervention (odds ratio [OR] for physical or emotional punishment immediately post intervention = 1.20 (95% CI 0.79–1.82). There were no significant differences for positive and involved parenting, setting limits, and opinion on discipline, but caregivers in the intervention group had significantly lower odds of using positive discipline (OR = 0.65 (95% CI 0.53–0.80). Families First did not prevent punishment in a setting with low levels of reported punishment but should be tested in a setting with higher levels or among people selected for risk or presence.