What People and societies suffer from different forms of dis/honesty and un/cooperativeness. Providing knowledge on their determinants can help understanding and, at best, even preventing socially undesirable behavior. By looking at adults and children, we will not only provide corresponding information for the development of immediate interventions, but also for the development of educational tools equipping the coming generations with a more sincere and collaborative nature when self- and collective interests are at odds. Why Dishonest and uncooperative behavior occurs daily, ranging from the private context, over semi-public and organizational settings, to international nationwide agreements. With the project, we will examine the interplay between person and situation factors in shaping dishonest and uncooperative behavior. How We will conduct a series of experiments on the determinants of dis/honesty and un/cooperativeness, always considering the interplay between person and situation factors. Specifically, we will conduct laboratory and field experiments, looking at the behavior of adults and children.