The eyes provide important information for decoding the mental states of others. In this fMRI study we examined how reading the mind in the eyes develops across adolescence and we tested the developmental trajectories of brain regions involved in this basic perceptual mind-reading ability. Participants from three age groups (early adolescents, mid adolescents and young adults) participated in the study and performed an adapted version of the 'Reading the Mind in the Eyes task', in which photographs of the eye region of faces were presented. Behavioral results show that the ability to decode the feelings and thoughts of others from the eyes develops before early adolescence. For all ages, brain activity was found in the posterior superior temporal sulcus during reading the mind in the eyes relative to a control condition requiring age and gender judgments using the same eyes stimuli. Only early adolescents showed additional involvement of the medial prefrontal cortex, the inferior frontal gyrus and the temporal pole. The results are discussed in the light of recent findings on the development of the social brain network.