If one were to enumerate the most influential and universal social behaviors in human societies, gossip would undoubtedly be one of them. Exchanging social information is fundamental for partner selection, social control, coalition formation, but it also plays a role in social comparison and group cohesion, just to name some of its main functions. The most frequent topics of human conversations are other people’s reputation, actions, choices, and attitudes.

In this talk I will claim that, far from being mere idle-talk, gossiping is a socially complex activity people intentionally engage in because of what they believe about others and how they want others to behave. I will then present a cognitive theory of gossip and reputation in order to point out that choosing an addressee, selecting the topic and deciding whether and how to give a specific information are actions pursued according to individuals' beliefs and goals. Finally, I will try to show the complex interplay between the micro-level of agents' motivations and the macro-level of collective behaviors by presenting some results from experimental studies within the framework of Agent-Based Social Simulation (ABSS). In this computational approach, social phenomena may emerge as a result of interactions among heterogeneous artificial agents endowed with internal representations of themselves, their peers and their environment.