Parenting programs can enhance positive parenting, reduce harsh parenting, and positively impact children's development. This two-arm randomized controlled trial examined the effectiveness of the parenting program, the ACT Action Program - Raising Safe Kids, on parenting practices (primary outcomes), parental sense of competence, stimulation activities, and children's behaviors (secondary outcomes) in low-income families. The sample consisted of 1,310 caregivers and their 0-to-6-year-old children from 17 municipalities in a Brazilian state, with the majority receiving cash transfers (governmental monetary support for families facing vulnerabilities). The caregivers were randomly allocated into the intervention (IG,