As chairman ofthe Consultative Programming Committee for Spatial Research (PRO) it is a great pleasure for me to present to you this publication. The theme of this publication, sustainable urban development, is one ofthe major issues oft day. In its Vision on Planning Research in the 1990's, PRO has given priority to several aspects of sustainability, as part ofthis important research field at the interface of spatial planning and environmental policy. Attention has been especially requested for both research into elements of spatial design which facilitate and encourage environment friendly behaviour, and for research into to the pre-conditions for and results of applying ecological principles in cities. These two priorities can together be regarded as the focus of a cluster of interrelated research questions. PRO has formulated these priorities in order to indicate the direction in which research projects ought to develop. As a result of the overall aim to coördinate and synchronise important research for spatial planning, PRO is not only a platform for discussion but also an intermediary and catalyst, facilitating the type of specific consultation that is needed to coördinate research efforts. In this respect PRO has been active in facilitating this publication on sustainable urban development, in order to promote research coöperation, both nationally and intemationally, with respect to the cluster of questions mentioned above. These activities may be seen as typical for the general functioning of PRO, because PRO is a platform for consultation in which all parties involved in spatial planning research, discuss general topics to be developed and the facilities for this research to be carried out. The studies and advice provided by PRO, are intended to direct attention to questions in management practice and its related research that are not easily solved or do not receive the attention they require. In general these are questions which are connected to new developments in society - developments whose consequences for environmental planning have not been translated into policy problems. lamsure that the various papers will provide a great deal of interesting information about the state of the art. As the topic of sustainable urban development is still quite new and in progress, l am also sure that this information will reveal a variety of contrasting approaches.