Urbanisation is “a process by which an increasing proportion of a national population lives in towns and cities”. The aim of this Future Issue is to analyse current trends brought about by urbanisation, including future risks and opportunities in both developing and developed countries. This paper is based on an in-depth study of a broad collection of foresight studies, as well as several policy reports on urbanisation. The expectation is that the extraordinary rapid growth of urbanisation will continue, resulting in more megacities and minicities. Cities provide people with many opportunities, such as access to infrastructure, employment and education. However, this depends on the individuals themselves, as well as on the cities. If local governments fail to adapt urban planning to a changing situation, this may create risks. Some of the safety and security implications being a decline of the infrastructure, terrorism and crime, epidemics, or more air and water pollution. All of these may occur in both developing and developed countries, but in this respect special attention should be paid to the developing countries. Here, the capabilities of their governments often do not match the expectations of their citizens, which may lead to political instability. This is not to say that urbanisation in the developed world will not have its own safety and security effects. Cities in developed countries may e.g. be faced with a declining infrastructure, traffic bottlenecks, extreme weather events, and other issues related to safety and security.