This report presents the preliminary results of the final season of the UNESCO Libyan Valleys Survey, that took place in October 1989. The fieldwork was divided in two parts. The first part of the work concentrated on the settlements in the Wadi Buzra, a northern tributary of the Wadi Sofeggin, especially at Souk el Awty. The major monument here consists of a substantial church (published elsewhere by D. A. Welsby in this volume), which was investigated by architectural survey and limited excavation, as were the surrounding late Romano-Libyan farms. The modern name of the settlement suggests that it may have been an important centre in Islamic as well as the Romano-Libyan periods, but the excavation did not obtain conclusive chronological evidence. The second part of the fieldwork was in the Wadi Umm el-Kharab, a southern tributary of the Sofeggin. Here, the team carried out a detailed study of a series of fortified farms of the later Romano-Libyan period, to compare with the open farm of the earlier Romano-Libyan period in Wadi el Amud previously studied by the project. An analysis of the constructional details of the major farms was integrated with excavations to recover stratified dating evidence from within the farms and faunal and botanical evidence from associated middens, and with a survey of the water-control systems of walls down the length of the wadi. The study indicates that the wadi was settled by people living in open farms and nucleated settlements in the first four centuries AD, but that by the fifth and sixth centuries AD these were replaced by fortified farms. There is evidence that the occupants of the fortified farms cultivated the wadi within an integrated economic system characterised by centralised food storage, rather than as independent units.