Originally coined to signify a style of pottery in southern Iraq, and by extension an associated people and a chronological period, the term "Ubaid" is now often used loosely to denote a vast Near Eastern interaction zone, characterized by similarities in material culture, particularly ceramic styles, which existed during the sixth and fifth millennia B.C. This zone extended over 2,000 km from the shores of the Mediterranean to the Straits of Hormuz, including parts of Anatolia and perhaps even the Caucasus. The volume contains twenty-three papers that explore what the "Ubaid" is, how it is identified, and how the Ubaid in one location compares to another in a distant location. The papers are the result of "The Ubaid Expansion? Cultural Meaning, Identity and the Lead-up to Urbanism," an International Workshop held at Grey College, University of Durham, 20-22 April 2006.