The reader studying this chapter is advised to have at hand a dried innominate bone or pelvis. In order to interpret accurately the radiological features of a fractured acetabulum, it is necessary to pursue in a disciplined fashion an orderly study of each standard view, then to put these together in three dimensions, comparing when necessary with the appearance of the opposite side, and finally to relate the findings to the radiological features of the columns of the acetabulum. Each landmark must be followed in turn, and scrutinised for possible traversing fracture lines; it is important to note whether at the site of such a break, there is frank displacement or not. Treatment should not be commenced until a full understanding is achieved and, most important, during the consequent well-planned operation the surgeon will know what to expect and not have to try to analyse the fracture during the procedure.