Adolescence places high demands on inter-personal interactions and, hence, on the extraction and processing of social cues. Here we assess longitudinally the development of brain activity within a network implicated in social cognition-the action observation network. We performed activation likelihood estimation meta-analyses to define regions of interest based upon the mature action observation network of adults. Using functional magnetic resonance imaging, we then examined developmental trajectories of functional brain activity within these brain regions. Using this approach, we reveal quadratic trajectories within a fronto-parietal network previously shown to demonstrate correlated morphological development.