This paper introduces the concept of participatory sensing, which tasks everyday mobile devices, such as cellular phones, to form interactive, participatory sensor networks that enable public and professional users to gather, analyze and share local knowledge. An initial architecture to enhance data credibility, quality, privacy and ‘shareability’ in such networks is described, as well as a campaign application model that encompasses participation at personal, social and urban scales. Example applications are outlined in four areas: urban planning, public health, cultural identity and creative expression, and natural resource management.