The Commentary entitled “Making Humans a Multi-Planetary Species presents the vision of Elon Musk, CEO of SpaceX, for future manned trips to other planets and specifically what will be needed to create a self-sustaining city on Mars. The article, drawn from Mr. Musk’s presentation at the 67th International Astronautical Congress, is published in New Space, a peer-reviewed journal from Mary Ann Liebert, Inc., publishers. The article is available free on the New Space website until July 5, 2017.