As one writer recently staled, 'unless you intend to rely on blind luck, information is clearly crucial to urban management and decis^on“maMng, (Cartwright 1989: 8). Even though everyone would accept that data and information are the raw materials of decision-making, data and information issues currently seem to be taking second place to technological issues in the current phase of the development of geographical information systems. (GIS). The factor which will determine whether or not GIS become more globally accepted will be their proven usefulness to decision-making in practical planning environments. This, in turn, will depend on how well GIS are integrated into decision-making processes and on the quality of the underlying data structures which support GIS. The issues which remain to be resolved are how can GIS most effectively contribute to the creation of more robust and more accessible processes of social decision-making, how can GIS assist decision-makers to learn how to intervene at the right time, at the right place with the right policy instruments, and what data infrastructure is needed to support GIS in a policy-analytical environment?