The reasons why people go missing are both numerous and diverse. In most cases, people will leave on their own accord, sometimes to participate in illegal activities. The circumstances in which people return or are found can be equally diverse, such as suffering harm from violence or normal circumstances with no ill consequences. The Metropolitan Police of London have been developing guidance to front-line officers on how to respond to notifications of missing persons. This development included consideration in the application of a risk prediction score which could be used to prioritize cases and trigger the appropriate response. The purpose of this report commissioned by the Metropolitan Police was to first compile comprehensive descriptive information of the entire missing person population, both who and the outcomes, and secondly, based on this information inform the development of risk prediction procedures. The study consisted of a cross-section of 1,000 representative cases. The cases revealed a variety of situations, backgrounds, and outcomes. It was concluded that given the inevitable limitations of any risk prediction score, the police will always be required to exercise a good deal of professional judgment in missing persons cases, although informed by any available and usable empirical evidence on the risks of different outcomes. The Association of Chief Police Officers issued guidance to strengthen officers’ professional judgment in dealing with missing person cases. References