The question of increasing similarity of forms and ideas is an important one in the social sciences in general. There are two main—and strikingly different—ways to account for increasing social similarity. The first is through an evolutionary or modernization type of argument, where increasing similarity reveals parallel but discrete processes of fit and adaptation. The second is through a diffusionist kind of argument, where forms and ideas circulate and spread across many different kinds of borders. Comparing three variants of the diffusionist argument, this article explores the different notions of time and history that these three variants reveal and express. While history always seems relevant, the way in which it is understood and plays out clearly varies across types. In conclusion, we suggest that recent developments in sociological studies of diffusion call, beyond history, to genealogical or archaeological research strategies.