Collaborative Australian–Turkish archaeological investigations in north-eastern Anatolia, begun in 1988 in the Bayburt province (then an ilçe of Gümüşhane), continued for six weeks during June–July 1994 with excavations at Sos Höyük near Erzurum. The decision to extend the limits of the research project beyond the Bayburt plain, eastwards into the adjacent province, was based primarily on the need to address questions raised by our work in Bayburt, most notably the apparent gaps in its culture sequence. Further, we were acutely aware that in order to establish a sequence for north-east Anatolia we would need to reexamine by systematic excavations the human settlement of the Erzurum plain, long known from the early campaigns of H. Z. Koşay and his colleagues at Karaz, Güzelova and Pulur, and I. K. Kökten's pioneering surveys. Our interest in the site of Sos Höyük was roused by material excavated during a three week campaign in the summer of 1987 by a team from Atatürk University (Erzurum) and Erzurum museum. While some of the material clearly keyed into the Bayburt sequence, much of it did not. A visit to the site revealed a dense surface scatter of artefacts, especially obsidian, and substantial stratified deposits exposed by the diggings of the local villagers. The potentialities of the site were clear. With the material excavated at Büyüktepe and collected in the Bayburt province overlapping and complementing that at Sos, we would move closer toward an understanding of cultural developments in north-east Anatolia.