In a French early childhood care and education system that is strongly divided by age and institution, the current research studies the collective life of children at the pivotal age of two to three years of age in four different early childhood settings: (1) a group of "grands" (nursery) in a "crèche" (daycare centre), (2) a "jardin maternel," (3) a "classe passerelle" and (4) a group including "tout-petits" in an "école maternelle" (nursery school). Our methods combine the observation of children and the point of view of professionals, obtained using visual aids (photos and videos). We analyse successively the institutional organisation of ages, material culture and professional practices. Depending on the ways in which their age is defined by these settings, we show how these settings create different experiences for children, which make them "petit" (at the "école maternelle") or "grand" (at the "crèche"). The interest of the "jardin maternel" and the "classe passerelle" is to show intermediate ways of framing the age of children two to three years old.