The last 10 years have seen a sudden rise in interest in the use of Geographical Information Systems (GIS) in historical research. This has led to a field that has become known as `historical GIS'. This development started in the more quantitative ends of the discipline but has spread to encompass qualitative research as well. Interest in historical GIS is not restricted to researchers who would previously have regarded themselves as historical geographers, but has in fact led to an increased awareness of the importance of geography from across the discipline of history. This paper introduces historical GIS and critically evaluates how it is affecting the practice of historical geography.