This is the story of Ruby at Square. As Square grew, we invested heavily in a service oriented architecture (SOA) and mainly used Java as our language of choice for new service development. Recently we finished a project, named Minecart, to deeply tie Ruby applications into our Java service infrastructure. To accomplish this we had to dive into the bowels of JRuby. To date, Square is roughly around 50/50 Java services vs Ruby services and everyone enjoys the benefits of a standard ecosystem. I will share many of our learnings along with a couple of practical examples and pitfalls for integrating Ruby into a custom Java framework.