One of the questions that non-archaeologists often ask us is how we find archaeo- logical sites. Today we often provide a pat answer about random or systematic sam- pling, or perhaps about fieldwalking. This does not do justice to what archaeologists actually do, or to the body of theory and methods we have built up. After decades of carrying out surveys with intuitive designs, in the 1960s some archaeologists began to deal more explicitly with the design of archaeological surveys. Some seminal articles on aspects of archaeological survey design followed over the next two decades but, unlike excavation methods, archaeological survey has received no comprehensive treatment that could serve as a guide to survey practitioners. The main purpose of this book is to fill this gap. In addition, most archaeologists have been reluctant to discuss aspects of survey other than sampling and a few of the factors that influence detection probability. They have also almost completely ignored the large body of literature on search theory that cognate fields have generated. In an attempt to put archaeological survey on a consistent theoretical "and methodological basis, I have drawn on research in archaeology, math- ematical earth sciences, and operations research. This will result, I think, in some sur- prises for archaeologists, who have sometimes struggled to identify and understand sur- vey problems that other fields had already studied intensively.