This thesis contributes to the domain of awareness information. Awareness information can be viewed as a fundamental building-block of social media, visualizing people and their activities in an online setting. With life becoming more and more influenced by social media such as Facebook, Flickr, Twitter, Linkedin and Digg, it becomes important for designers of social media to have an understanding of how users respond to awareness information. An online gallery of pictures was developed and equipped with a chat and a basic awareness information system. Usage data was collected by the system and analyzed combining qualitative as well as quantitative approaches aiming to explore the influence awareness information have on the usage of the system. The analysis reveals that awareness information is a powerful tool triggering social behaviour. It is, at the same time, challenging to implement in a way that it provides a sound environment for social interaction. This was manifested by co-present users both stayed longer in the system and also was inclined to take a different path through the gallery than the solitary user. However, the interaction that took place in the gallery was characterized by frequent conversational break-downs and irritation among users. Results indicate that this is, in part, due to the lack of built-in social norms guiding users in their activities in the system. Subsequently, it is important to facilitate the creation, recreation and reinforcement of social norms when designing social systems.