When working in shared physical spaces, individuals develop a rich sense of awareness that greatly facilitates their collaboration toward a common goal. They gather and share information freely; they gain a sense of what others know which allows them to ask the right person for help; and they come to understand other's goals which gives them a richer sense of purpose. This richness seems to be missing in electronic contexts. We propose a methodology for recapturing it. Our approach is called activity-based computing (ABC) which draws its principles primarily from activity theory, which divides human behavior into hierarchy of activities, actions, and operations. We observe that computer systems today are action-based which results in their lack of awareness of high-level activity context and motive. ABC performs activity-level analysis using probabilistic models and tacit data mining and provides efficient visualization as a user interface.