Successful social interaction is not something that occurs from birth. Infants and children undergo considerable change in their ability to feel with and understand their fellow human beings. Therefore another focus of our research is on the development of social behavior. We are particularly interested in understanding the changes in children’s ability to take other people’s perspectives, grasp their own feelings as well as those of others and to control their own emotions and behavior. One key component of this is endeavor is to understand the maturational time-course of the neural mechanisms underlying these behaviors. Our studies focus on children and adolescents between 4 and 17 years of age. By using paradigms developed and traditionally used in a game-theoretical context, we study the development of prosocial behavior and affective decision making in a manner that is highly ecologically valid.