Peace education has primarily been studied and discussed as forms of educational activities in class room settings. Consequently, expected outcomes of these activities are expressed in terms of increasing knowledge and understanding of the concept of peace, and related concepts such as democracy and social justice. A considerable number of curricula and programs for peace education have been produced, specifying instructional content and methods.Since the 60´s several empirical studies have been conducted on how children of various ages and with various social and cultural backgrounds understand meanings of peace. The results indicate systematic variations in ways of understanding and describing what peace means. Peace is defined, understood, reflected upon and discussed differently by younger children compared to older ones, by boys compared to girls, and by children from one country compared to children from other countries. However, similarities in views of peace are also reported. Available empirical data implies that most children, no matter of socio- cultural background or age, regard peace as -on one hand- something opposite war and quarrels, and -on the other- as something fundamentally social and positive (e.g. friendship). These elements have been suggested to constitute a common core in children´s on-going social elaboration of social norms and values such as tolerance, solidarity, social justice and equality.In this paper I will discuss in what way the school context may support and/or impede such further elaboration of social values. Drawing on empirical data from some recent studies, I will show that visible as well as invisible curricula are at hand, and that children´s emerging understanding of what peace -and related social values- means, largely is a matter of socio-constructive social practice among peers in a shared school context where adults not always are present.