Java still ranks at the top of the TIOBE index. The JVM is a trusted platform which has stood the test of time and is used widely to develop complex, reliable and high performing systems. By choosing to target the JVM, Clojure can leverage all of its power while bringing new ways of writing reliable software into the mix. But why should a Java developer care? In this talk we will examine the main differences between Java and Clojure, pointing out new patterns and tools and finally ending with a discussion of the concurrency and parallelism abstractions provided by Clojure. By the end of this talk you will have developed an understanding of Clojure’s fundamental building blocks for writing concurrent applications.