Maps, censuses and other sources of geographic and demographic information are common reference tools for historians, but integrated computer hardware and software systems designed for the preparation, presentation, and interpretation of such geographic and spatially-referenced data are rarely intended for use outside the Earth Sciences. This guide to good practice is written for historians who want to use Geographical Information Systems (GIS) as part of their research. It defines GIS and outlines how it can be used in historical research, describes how to create and get data into a GIS database, explains how GIS can be used for simple mapping and more advanced forms of visualisation, and discusses the various ways to analyse data within GIS. It includes case studies from a variety of historical projects that have used GIS and an extensive reading list of GIS texts relevant to historians. No prior knowledge of GIS has been assumed.