Playing is a common part of children’s leisure time, and with children spending an increasing amount of this time in school-age childcare, in both Sweden and England, staff have the responsibility to facilitate play. The way play is conceptualised by staff may lead to different aspects of play being facilitated. These play practices are enabled and constrained by the arrangements of what this dissertation calls the school’s play practice architecture, i.e. where play practices are intertwined with a school’s practice architecture. The aim of the research was to explore how staff talked about play and how to facilitate it, how concepts of play contributed to different play practices and how it might be possible to transform play practice architectures. The research draws on conversations with staff in school-age childcare settings in two Swedish and one English school during an action research project. Just as action research was used to disturb and change practice in order to understand it, concepts from Deleuze and Guattari’s philosophy (1980/2004) were put to work to disturb taken-for-granted concepts of play in order to explore how play works. Article I explores what the staff talked about in relation to play and its facilitation. The conclusion is that the ability of staff to interpret children’s play as children exploring their agency is crucial when facilitating play in a learning institution. Article II examines some discursive orders about play in school-age childcare and goes beyond them by conceptualising playing as becoming-different. The article argues that when foregrounding play, staff recognised children and themselves as becoming-players. Article III investigates how to think practice as constant change. For any practice, planning is required, and yet the unexpected keeps happening. When playing was conceptualised as a “What If? As If” approach, which allowed for potentialities to become actualised, then this approach was also useful as an approach in practice. The analysis suggests that when engaging in a playing practice, practitioners develop new knowledge and simultaneously change social situations. The practice of playing, whether intentional or unintentional, can not only disturb but also transform play practice architectures. The practice of playing is sensitised to the disturbances caused by playing and also puts itself “in play”. This opens up for a continuous de- and reterritorialisation of play and playing in school-age childcare practice.