The Archaeology of 'Underdog Sites' in the Douro Valley brings together the best presentations from the eighth and ninth meetings of Archaeology of the Douro Valley, held in Avila and Astorga (Spain), respectively in 2018 and 2019. However, instead of a simple collection of articles, the aim of this publication is to show the importance of projects that have been left in the background despite obtaining interesting archaeological data about the occupation of this valley and its evolution. Moreover, we must take into account that many of these projects support new activity in a rural territory that is increasingly neglected politically and economically. Hence the use of the term 'underdog', defined as a person or group of people with less power or money than the rest of society. Overall, the volume provides a general and interdisciplinary view of the different types of occupation in the territory of the Douro Valley. The chapters are divided into four sections, three of them chronological: Prehistory and Protohistory; Antiquity and Late Antiquity; and the medieval and modern ages. The last section is thematic and includes diachronic studies, museology, and the archaeology of mining. Therefore, the present volume is a medium to showcase the latest research carried out in this important territory and to contribute to knowledge of its history, updating the archaeological state of the art in the valley and presenting results that may be used in the most diverse types of comparative studies.