The case for the compact city remains largely unresolved. The debate in previous chapters has indicated a range of issues in which there is a degree of uncertainty. Competing and conflicting claims, which of necessity are argued from an incomplete knowledge base, exist in theory, in the concept of sustainability, and in relation to environmental, economic and social issues. However, there is an imperative to gain a deeper understanding of the compact city. This is particularly important as policy is promoting new compact forms, while at the same time the results of implementation are largely unknown and hard to predict. Yet the very complexity of cities means that such knowledge is hard to gain.