Context awareness allows applications to adapt themselves to their computing environment in order to better suit the needs of the user. Such a capability is critical to pervasive computing because it promises to reduce the demand for human attention, which arguably is the most limited resource in an environment saturated with computing and communication capability. This paper reflects on our experiences in enabling and exploiting context awareness. These include a general context service that provides infrastructure support for context collection and dissemination, a programming abstraction for supporting the composition of context data and the continual rebinding of context sources, and a series of context-aware systems that enable the unified communication between people and between people and computers. Conducting the work in an industry research lab, we have taken an incremental approach to tackling the problem space and had it as our goal to affect both the state of the art and the state of the practice. The paper concludes with a discussion on some of the challenges in the wide deployment of context-aware technologies.