Repeat photography is a technique of detecting changes in the landscape by comparing old and more recent photographs taken at the same place. Information gained is used to detect landscape change as one component of historical ecology. Understanding the causes of any change detected requires additional information. The technique was pioneered in vegetation ecology in Arizona and has since been applied in many other parts of the United States. After a description of the technique, the American experience is reviewed and the problems of detecting change and assigning cause are discussed. The relatively few Australian examples are briefly summarised. There are many limitations of repeat photography, but these can be controlled through a careful approach. Although repeat photography has rarely been used in Australia, it has significant applications in education, in understanding past changes and in helping to help predict future changes in vegetation.