The Census Interaction Data Service (CIDS) is funded by the Economic and Social Research Council in the UK to provide access for social science researchers and students to the detailed migration and journey-to-work statistics that are collected by the national statistical agencies. These interaction data sets are known collectively as the Special Migration Statistics (SMS) and the Special Workplace Statistics (SWS). This paper outlines how problems of user access to these data have been tackled through the development of a web-based system known as WICID (Web-based Interface to Census Interaction Data). The paper illustrates various interface features including some of the query building facilities that enable users to extract counts of flows of particular groups of individuals between selected origin and destination areas. New tools are outlined for assisting area selection using digital maps of census geographies, for planning output and for adding value to the data through analysis. Mapping of flows of migrants between London boroughs and the rest of the UK demonstrates the value of the data. The paper begins with a summary of the data sets that are contained within the system and an outline of the system architecture.