 Human cooperation can fundamentally shape many important economic outcomes of individuals and groups. Individuals differ in their cooperative behavior and these differences remain even after explicitly controlling for differences in institutional settings, technologies and beliefs under which cooperative behavior is studied, thereby identifying differences in underlying individual preferences for cooperation. These preferences for cooperation not only exist but even matter a great deal for cooperative behavior in the field, namely the management of common pool resources. The focus of this project is on analyzing cooperation among first graders, as previous research has shown that (1) the level of malleability of preferences and skills seems to be higher for young children and (2) differences in development at this age are strong predictors for life outcomes. A significant contribution of this project consists of designing, testing, and implementing a new informative measure of cooperation, as standard designs of “classical” cooperation games, e.g. public good games, might not be suitable for being used with young children. In case of successfully identifying an age appropriate measure of cooperation, we plan to realize a large-scale field study in the school context to investigate whether preferences for cooperation are shaped by the actual experience of cooperation for a substantial period of time, and, to what degree the social environment of individuals mediates this effect. This project is funded by the Germany National Science Foundation (DFG).