This study of Roman Republican military castramentation evaluates both historical and archaeological evidence. There are two main areas of enquiry. The first is a description of a Roman army camp given by the Greek historian Polybius. The second is concerned with the only significant body of published archaeological evidence of Republican camps, largely the work of Adolf Schulten, who reported on the excavations which he conducted in Spain during the early years of the 20th century. The present author offers some kajor new interpretations of the archaeological evidence together with some fresh observations derived from fieldwork.