Does child-mother attachment predict and mediate language and cognitive outcomes? A series of meta-analyses

•Through meta-analyses of 125 studies (N = 9,213 children), this study shows medium-sized associations between child-mother attachment security and child cognition and language.•Additionally, using meta-analytical structural equation modeling, this study shows that both maternal sensitivity and child-mother attachment contribute to child cognitive and language outcomes.•This study helps shed light on the developmental processes by which parenting and early childhood relationships influence cognitive and language development in children.