Context–Aware Composition is a technique to overcome the complexity of wireless discovery, device selection, and establishing connections to other computers in an environment where potentially tens or even hundreds of other computers may reside. In this paper, we present our work demonstrating the benefit of using context to facilitate the discovery process through sensing. We describe our sensor platform, the Context Card, and discuss how the Sensor Actuator API (SAAPI) is used to collect and distribute sensor data. We also show how context can be used to create multi-modal composition commands and provide a quantitative evaluation of a multimodal position sensing system to support context-aware composition.