This year marks the 20th birthday of the Open Source movement. Wikipedia highlights on aspect crucial to open source software development by describing it as “collaborative development from multiple independent sources”. During the past decades people of all trades have found ways to collaborate on OSS projects that span organisational, timezone and geographic boundaries. For years in particular those active in OSS projects have been advocating to bring the collaboration practices they knew of open source over to their respective in-house teams. The resulting practice goes under multiple names: Open Development, Internal Open Source, Inner Source. For the past year, Europace AG, a Berlin based FinTech, has been piloting InnerSource efforts. During that time, work was closely following (and contributing results back to) innersourcecommons.org - a global, cross-organization initiative to further InnerSource practices that “apply the lessons of Open Source to all software engineering, using collaboration and transparency to increase quality, speed, and developer joy”. This talk will take you on a journey from a vague idea towards an organisation that embraces Open Source collaboration techniques internally. Towards an organisation in which a growing number of developers are starting to get involved with Open Source projects themselves.