Speakers: Nathaniel Manista, Augie Fackler Large codebases written by many authors over long periods of time too often become tragedies of the commons riddled with complexity and technical debt. We’ll cover the pathologies that specifically encumber collaborative software development (drawing on examples from the Mercurial codebase) and describe alternative practices, their efficacy, and the costs of adopting them. Slides can be found at: https://speakerdeck.com/pycon2016 and https://github.com/PyCon/2016-slides