This study provides a rigorous assessment of a community-based early child development (ECD) intervention to understand the drivers of caregivers' reading and playing practices in a low-resourced township in South Africa. Mentors visited 157 homes biweekly (2474 observations from 2019-21; children ages 0-5), completing surveys regarding caregiver behaviors and engagement. One hundred and fifty-seven caregivers (mostly Black, Zulu women) participated in the program during this time period and completed surveys biannually on their support system (modified version of the Multidimensional Scale of Perceived Support) and ECD beliefs (modified versions of the Parental Play Beliefs Scale and the Parent Opinion Survey). Longitudinal Hierarchical Linear Model revealed that several behaviors and beliefs significantly predicted positive parenting behaviors. Regression discontinuity plots suggest that positive parenting behaviors could continue and even improve following Covid-19 shutdowns, especially in homes with more intervention visits. This paper provides translational evidence on tangible ways interventions can engage caregivers in stimulating ECD behaviors. Highlights •This study analyzes data from a South African ECD intervention targeting caregiver reading and playing practices through a relational home-visitation program.• Caregiver engagement was the changeable individual difference that best predicted caregiver reading and playing behaviors.• Time in the program, social support, and hope that children will have a better future significantly predicted caregiver reading and playing behaviors.• Participants who were in the program for over a year before the pandemic were best able to sustain positive beliefs of child development after the shutdown.• Caregiver involvement and reading and playing improved even after the pandemic shutdown, especially in homes that had more intervention visits.