Many theories of play are not very specific in their analysis of the evolution of play after preschool age. One of the problems is that they are based on a developmentalist assumption that considers play basically as a quality of childhood. This chapter describes an activity theory approach to play, based on Cultural-Historical Activity Theory that conceives of play as a way of accomplishing (cultural) activities, which can continue throughout human ontogeny. This approach avoids developmentalist assumptions and sees play mainly as a cultural problem. Play is now conceived as any rule-governed activity that engages the actor and allows the actor some degrees of freedom with regard to the accomplishment of the activity (e.g. redefinition of goals and tools and interpretation of rules). From this point of view, the development of playing is manifest in the actors’ improvement of the ability to use more complex rules of activities (social rules, technical rules, conceptual rules and strategic rules) for participation in involved ways in those activities, while using the degrees of freedom that are permitted.