There is increasing awareness that the intergenerational transmission of (dis)advantages is filtered through intra-familial dynamics, in particular parenting practices. Surprisingly, fathers’ role in this transmission is often neglected. The current paper examined fathers’ influence on children’s cognitive development, specifically the role of fathers’ relative involvement in parenting in the intergenerational transmission of (dis)advantages. Using data from 2,027 families in a Dutch prospective cohort study, our SEM-analyses showed direct effects of fathers’ relative involvement in playful activities on children’s cognitive development. Additionally, our study yielded some evidence for the hypothesis that fathers’ relative involvement in playful activities mediates the impact of fathers’ educational attainment on children’s cognitive development. This suggests that fathers’ involvement in parenting functions as an underlying mechanism for maintaining social class disparities in children’s cognitive development. Our findings suggest that programs that encourage equal involvement of fathers and mothers in playful activities may help promote children’s cognitive development.