New technologies impose to web-based groupware systems (which allow a group of user to work together through the system) to adapt their content to the constraints of such technologies and to the user's mobile situation. We propose a context-based filtering process which aims at adapting the awareness information delivered to mobile users by these systems. Awareness information refers to the knowledge one has about her/his work group, his/her colleagues and theirs activities, in order to coordinate his/her own activities in this group. This filtering process relies on a model of context which integrates both a physical and a collaborative dimensions and a model of profiles. These profiles are descriptions of user's potential contexts and express the awareness information filtering rules to apply when the user's current context matches one of them. These rules reflect the user's preferences given a context. The filtering process performs in two steps, one for identifying the profiles which a potential context matches with the user's current context, and a second for selecting the awareness information. An implementation of our proposition and the results of the first tests performed are also described.