The continued growth of Internet of Things (IoT) and mobile has forced applications to scale in unprecedented ways. The desire to easily scale an application has also moved many applications onto Infrastructure as a Service (IaaS) which charges for every single resource. Reactive applications have become popular because they can scale with less resources. Switching from threaded to reactive programming can be daunting. This complexity is compounded when you need to secure your application in a world where every day brings the next big security breach. If you are committed to a reactive architecture but are blocked on how to secure it, then this talk is for you. In this talk Rob will demonstrate how to use the new reactive support in Spring Security 5. We will start with a simple application and incrementally secure it. Along the way we will learn answers to frequently asked questions, how to leverage the full power of Spring Security, and how to properly architect security in our reactive application.