The Indian government has undertaken a major effort to issue Unique Identification Numbers (UID) to its citizens. This chapter examines the Social Security Number system in the US, and investigates other UID projects in Europe. Based on these understanding and other information around UID systems, the authors discuss possible issues that are expected to arise in the implementation of UID system in India. They articulate how biometrics is being advocated by the proponents of the system in India for unique identification. The authors elucidate the social, ethical, cultural, technical, and legal implications / challenges around the implementation of a unique identification project in India.