Social preferences have been shown to be an important determinant of economic decision making for many adults. We present a large-scale experiment with 883 children and adolescents, aged eight to seventeen years. Participants make decisions in eight simple, one-shot allocation tasks, allowing us to study the distribution of social preference types across age and across gender. Our results show that when children and teenagers grow older, inequality aversion becomes a gradually less prominent motivating force of allocation decisions. At the same time, efficiency concerns increase in importance for boys, and maximin-preferences turn more important in shaping decisions of girls.