This study contributes to the understanding of how early parenting interventions implemented in low- and middle-income countries during the first 2 years of children's lives are sustained longitudinally to promote cognitive skills in preschoolers. We employed path analytic procedures to examine 2 family processes--the quality of home stimulation and maternal scaffolding behaviors--as underlying mechanisms through which a responsive stimulation intervention uniquely predicted children's verbal intelligence, performance intelligence, and executive functioning. The sample included 1,302 highly disadvantaged children and their mothers living in rural Pakistan, who from birth participated in a 2-year, community-based, cluster-randomized, controlled trial designed to promote sensitive and responsive caregiving. Family processes were assessed at 2 developmental time points using parent reports, ratings of home environments, and observed parent-child interactions. Cognitive skills at age 4 were assessed using standardized tests. Controlling for socioeconomic risk (e.g., wealth, maternal education, food insecurity) and individual factors (e.g., gender, growth status), the quality of current home stimulation as well as both earlier and concurrent measures of maternal scaffolding independently mediated the intervention effects on cognitive skills at age 4. In addition, the intervention had a significant direct effect on executive functioning and performance intelligence over and above significant family processes and other covariates. We highlight implications for future program design and evaluation studies.