Maltreated children are particularly susceptible to adverse self-regulation strategies, but the mechanisms whereby this risk is conferred is understudied, as is their influence on trajectories of change in self-regulatory abilities over time. In this study, three mediators (positive parenting, positive family expressiveness, and maternal reminiscing quality) were examined as processes through which maltreatment influences three dimensions of child self-regulation (emotion regulation, lability/negativity, and inhibitory control) across three time points (baseline, 2 months, and 6 months later) using longitudinal mediation analysis with latent growth modeling. Participants included 154 maltreating, and 82 demographically matched, nonmaltreating mothers and their 3- to 6-year-old children (N = 236). Maternal reminiscing quality mediated relations between maltreatment and lability/negativity at 6 months, and change across time in emotion regulation and inhibitory control. These findings highlight maternal reminiscing quality as a mechanism by which maltreatment influences multiple dimensions of child self-regulation, and their developmental trajectories.