The articles in this section are based on a Social Science History Association roundtable organized in 2008 in response to Donna R. Gabaccia's presidential call “It's about Time: Temporality and Interdisciplinary Research” (see Gabaccia 2008; see also Gabaccia 2010). Her emphasis on questions of periodization resonated with concerns with which we had grappled for a decade. The questions that the roundtable and these articles address initially emerged from our experiences as teachers of a course on world history with a temporal frame of a few centuries (1450 to the present). But the course that really forced us to confront the challenges of periodization is one we introduced in the fall of 2009 on “the family from 10,000 BCE to the present.” In trying to connect research from around the globe on the domestic group as a site of world history to narratives that begin with human origins, we were struck by the inappropriate presumptions embedded in most conventional periodizations. Our inherited vocabulary of terms to describe eras, ranging from “the Neolithic revolution” to “early modern,” implicitly place all regions of the globe on a yardstick measured against European temporalities and based on activities typically gendered male.