You've downloaded and installed open source libraries, required them as Composer dependencies, and perused the source code of countless GitHub repositories. Now, you're ready to help others by creating your own Composer package. So, what does it take to build and publish an open source library? In this Talk, we'll take a look at some of the common patterns open source PHP libraries follow. Along the way, we'll cover: evaluating libraries for quality, common filesystem structures, the importance of tests and how to run them on Travis CI, publishing to Packagist, interacting with a community, and more. By the end of this workshop, you will have all the tools you need to distribute your own Composer package.