A theoretical framework can help physiotherapists understand and promote recovery of function in children and youth with acquired brain injuries (ABI). Physiotherapy interventions for this population have traditionally been based in hierarchical-maturational theories of motor development emphasizing the role of the central nervous system (CNS) in controlling motor behaviour. In contrast, Dynamic Systems Theory (DST) views movement as resulting from the interaction of many subsystems within the individual, features of the functional task to be accomplished, and the environmental context in which the movement takes place. DST is now a predominant theoretical framework in pediatric physiotherapy. The purpose of this article is to describe how DST can be used to understand and promote recovery of function after pediatric ABI. A DST-based approach for children and youth with ABI does not treat the impaired CNS in isolation but rather emphasizes the role of all subsystems, including the family and the environment, in influencing recovery. The emphasis is on exploration, problem solving, and practice of functional tasks. A case scenario provides practical recommendations for the use of DST to inform physiotherapy interventions and clinical decision making in the acute phase of recovery from ABI. Future research is required to evaluate the effectiveness of interventions based in this theoretical framework.