MobileConfig is Meta’s internal tool for the authoring and distributing configuration values across its many mobile apps and platforms, including Facebook, Instagram, and Oculus. Using MobileConfig, a developer can make a configuration change in minutes and have it distributed quickly and reliably to the billions of users who use our apps. Developers use the system to safely roll out mobile features, configure our many apps, and perform experimentation. We also provide a set of tools that give developers insights into the rollout of config values and allow rapid deployment of configuration values in emergencies. In this presentation, we will discuss some core features of MobileConfig, including our consistency model, performance optimizations, and how mobile configuration can push mobile agile software development to the extreme.