Since 2006, Udaan--a school-based adolescent education program in Jharkhand, India--was the only at-scale state-run program in the country. To determine factors that contributed to Udaan's scale-up and longevity, this study drew information from programmatic reports and interviews with the Centre for Catalyzing Change staff. Key factors for Udaan's success included an enabling policy environment, a willing government that supported and operationalized the program, a knowledgeable and committed NGO partner, sustained funding, and a commitment to constant improvement through evaluation. Udaan provides an example of a well-designed, implemented, and evaluated school-based adolescent health program that has been operating at scale over a sustained period. Other programs in India and elsewhere can benefit from learning from Udaan's experience.