Over 12,000 fighters from at least 81 countries have joined the civil war in Syria, and the numbers continue to grow. A lot are young, often teenagers, and a fair percentage of those arriving from non-Muslim majority countries are converts to Islam. These and others who share their faith commonly express their motivation as a religious obligation to protect fellow Muslims from attack., There is considerable international concern at what these young men – and some women – will do once they leave Syria, and although almost all appear to go without a thought of what next, the experience of being in a war zone and exposed to the radicalizing influences of sectarianism and other forms of extremism are bound to have an impact on their ability and willingness to resume their former lives., The policy response so far has often focused more on prevention and punishment than on dissuasion or reintegration, but as the number of returnees increases, and the resources required to monitor their activities are stretched to breaking point, it will be important to examine more closely why an individual went, what happened to him while there, and why he came back. This paper attempts to provide some general context for answering those questions, and offers suggestions for policy development