The evolution of social media has introduced novel possibilities for work and interaction in organizations. The wiki technology is one important kind of social media technologies that is increasingly used to facilitate the creation and sharing of organizational knowledge within communities. Given the increasing use of social media in organizations and the lack of knowledge on their consequences for organizing, we use an affordance lens to explore the enactment of organizational wiki affordances. Using qualitative data obtained through interviews, field visits, and documents from two multinational organizations –CCC and IBM– we first identified eight affordances that describe various wiki possibilities and practices. We then identified four properties of these affordances including multiplicity, referential, situatedness, and communal. These properties represent the main contribution of the paper in that they extend the notion of affordance by theorizing new concepts that describe relational dynamics, situated and contextual conditions, and social factors involved in enacting, perceiving, and exploiting affordances.