This case study discusses how India has emerged as a leader in building on its biometric digital ID (Aadhaar) to reform service and program delivery. India moved quickly to consolidate the rollout of Aadhaar, and then to embed the unique Aadhaar number into program databases. A range of applications, including digital signature and payments, was then constructed on top of the Aadhaar foundation (the India Stack). The note elaborates on three programs, and specifically highlights achievements as well as challenges that need to be overcome for greater efficiency and inclusion.