There are some traits that are shared by successful open source projects aside from the interesting technical space they occupy. Those that grow (and last) give individuals a sense of ownership, openly collaborate on technical direction and peer review, and make it easy for new starters to contribute. They build a community around a codebase which often results in better quality and a longer lifespan, and do this while overcoming challenges of being geographically distributed and having members with competing interests and different personalities. There are lessons that we can take from Open Source communities to encourage engineering teams to build well together, with the end game being well-engineered, approachable software and a sense of satisfaction and growth for engineers.