Abstract: This essay examines the conflation between world and planet in H. G. Wells's turn-of-the-century science fiction. Writing when "world=planet" was not a given, Wells actively participated in the formation of the world-planet vocabulary across a range of genres and throughout the first half of the twentieth century. In particular, I look into the planetary experiments of his early fiction, where the materially limited planet continually thwarts the writer's attempts to equate that planet to the world he wished to develop as the ultimate political unit. Emerging through such attempts is a divergence between world and planet that enables us to think about the individual, the world, and the planet all on a commensurate scale, in a manner that is strikingly—and perhaps also troublingly—similar to what recent environmental discourse asks of us today.