Today, everyday people are increasingly able to create and share written and recorded media via the Internet. This phenomenon, now evident in the explosion of blogs and online social networks, is often called Web 2.0, or the New Media, and has created compelling new avenues for public discource, creative expression, and electronic commerce. The same forces that have given rise to these trends in media—affordable personal computers and cameras; pervasive connectivity; and consolidated data centers—are also acting to create a public that can objectively record, analyze, and discover a variety of patterns that are important in their lives. Through the use of sensors built into mobile phones (e.g., cameras, motion sensors, and GPS) and web services to aggregate and interpret the assembled information, a new collective capacity is emerging: one in which people participate in sensing and analyzing aspects of their lives that were previously invisible. In this document, we introduce the concept of Participatory Sensing, explore five hypothetical situations in which the process might have real world influence, and suggest short and long term measures that can promote our vision.