This article traces the contours of a new biometric project in India that aims to develop a universal biometric database for the unique identification of India’s residents (UID, The Indian Unique Identification Project). It was launched in 2009 and by mid-2013 registered 430 million enrolments, making it the largest biometric experiment in the world. What is the rationale for and structure of this new instrument of governance and how does it affect the relation between citizens and state institutions? We discuss the legal framing of the project and present an ethnographic case study about its implementation among poor people in Delhi. We argue that within the heterogeneous social space of India the biometric project has opened up a terrain for multiple social negotiations. While the new technology propels fantasies about a corruption free well-ordered society the implementation runs up against innumerable challenges. The project struggles to find a definite legal form and suitable goals. Furthermore, the emerging link between people, computer generated data and projects of governance remains weak. By unpacking the relation between new technologies, emerging legalities, cultural bodies and social classifications, we evidence that UID is not one but many projects. Rather than a truth statement about identity UID is a ground for testing new relations between citizens and the state. They concern political question of the desire for order versus fear of control, and epistemological question of the inter-relation between regimes of transparency and social complexity.