AbstractWhen looking for a crime suspect, the police may ask an eyewitness to construct a visual likeness (‘facial composite’) of the perpetrator, to be distributed to the public via newspaper articles, television programmes, or social media. The dissemination of facial composites can have a major impact on police investigations. It often results in a deluge of tips and could potentially influence the memory of other eyewitnesses in the case. In this article, we review research on how to interview eyewitnesses for the optimal construction of facial composites from memory. We discuss types of composite systems and their effectiveness, including the ‘gold standard’ of measuring effectiveness. We compare the question posed to the public when a facial composite is disseminated to face-matching tasks faced by immigration officials and store clerks, but then with the added difficulty of the image being a composite of unknown resemblance to the target. We also discuss the potential danger of composites contaminating other eyewitnesses’ memory, highlighting the lessons learnt from research on unconscious transference. We pose several challenges for future researchers and practitioners. We conclude that evidence-based guidance is lacking to inform the police on whether and how to use facial composites in their investigations.