At Monzo we have been using Compose since it was in alpha. As well as a chance to write more intuitive code, this also gave us an opportunity to build a library of reusable UI components, making it easier for our teams to build and deliver new features for our users, and allowing us to go beyond the limitations of Material Design. In this talk we will look at: how to go about implementing a design system and theming in Compose - either by extending Material or creating custom components; what changes you may need to consider around your existing architecture, navigation and testing when migrating to Compose; and how to communicate the changes between developers across different teams and to the business.