Many studies have identified the positive "link" between imaginary play and emotion regulation in laboratory settings. However, little is known about "how" play and emotion regulation are related in everyday practice. This article examines how families use play as a tool to support young children's emotion regulation in everyday family life. Two middle-class Australian families with children aged three years were studied over a six-month period (n = 30.75 hours of video observations and interviews). Findings show how manipulative play was used by parents during every day routines to mediate children's emotions. Parents and children interact "together" to create an emotional zone of proximal development (ZPD) through play, suggesting that the development of emotion regulation is not an individual practice as identified in the literature, but collectively constructed. This study opens a new angle for understanding for a dialectical relation between manipulative play and children's emotional development.