This special section was motivated by a resurgence in the view that it is impossible to investigate perceptual and cognitive development without considering how it is affected by, and intertwined with, infants' and children's action in the world. This view has long been foundational to the field, yet contemporary investigations of the effects of acting on cognition and perception have been limited. The research showcased in this section indicates that this trend is changing as researchers consider anew the ways in which cognition derives structure from action. The work presented here illustrates the breadth of these potential effects across ages and domains of development, and it highlights the breadth of methods that can be recruited to investigate them. This new research focus provides insight for the mechanisms by which action affects perception and cognition and at the same time reveals that much remains to be learned.