A general trend in our modern society is a growing complexity. It is therefore logical that in most countries there has been a definite tendency to give weight to issues of adapting also the physical space to this complexity and to find methods to do this in an efficient way, giving satisfactory use of land and other natural resources. During the twentieth century we have seen a very active development of legal instruments for this purpose, aimed at steering spatial planning and plan implementation according to the objectives and policies chosen. This book presents basic information on how different countries within the chosen area have tried to solve the problem of establishing suitable systems of steering spatial development by means of planning and implementation measures. For this purpose summary descriptions of the connected formal regulations in each country are given in an appendix while a comparative presentation and discussion forms the main text. This will give the interested reader an overview of the current systems in Western Europe, how they have influenced each other but still in many parts differ from each other.