10up open sourced their WordPress Best Practices (PHP, JavaScript, tools, and workflows) in late 2014. As the Director of Engineering at 10up, I drove this project and am the lead contributor to the docs. These Best Practices allow developers to build sites that scale, perform, and are secure one sites receiving millions of page views per day. They also standardize development practices in such a way that facilitates team collaboration. This talk will highlight some important parts of the Best Practices and reveal some valuable tips about how we (10up) engineer some of the most complex and most viewed WordPress sites in the world.