The transition to kindergarten is considered as one of the most significant developmental milestones in childhood. Although the significance of parental caregiving for child school readiness is well documented, it remains relatively unknown how dynamic interplay of maternal and paternal caregiving unfolds over time to promote school readiness, mediated by child characteristics. The present study used observed parent-child interactions to examine how maternal and paternal insensitivity across 24 to 36 months were similarly or differentially manifested in shaping school readiness in language and self-regulation skills among children from low-income families. Further, we tested whether children's adaptive engagement mediated the relations between parental insensitivity and school readiness. To these ends, this study used extant data from the Early Head Start Research and Evaluation Study (N = 453 families of mothers, fathers, and children; 51% girls). Latent difference score model revealed commonality in the similar effects of mothers and fathers on child early language, linking both maternal and paternal insensitivity at 24 months to poorer vocabulary skills in children at age 5. Additional findings showed specificity in the differential effects of maternal and paternal insensitivity on child functioning, such that maternal insensitivity predicted deficits in children's vocabulary and self-regulation skills indirectly through poorer child engagement, whereas paternal insensitivity directly predicted children's poorer self-regulation skills. The findings highlight the longitudinal processes of early maternal and paternal insensitivity with common and differential implications for school readiness.