The development of context-aware systems such as groupware or CSCW and ubiquitous systems require a significant understanding of specific tasks that the users will perform seamlessly in their everyday work.??In order to do this, we need to understand the users’ tasks and their knowledge to perform these tasks, and build a computational model reflecting upon users’ tasks and their knowledge. Most importantly, such systems need to be socially appropriate so that they can support human-human communication in an implicit and unobtrusive way, by constantly monitoring humans, their activities and their intentions. The traditional methods of requirements capture are not suitable to design and develop such systems.??In this paper, we discuss different models and theories that can help to gather requirements. Most importantly, a simulation can play an important role in the requirements engineering processes of such systems.