Do two images show the same person? Intuitively, people assume image comparison is a straightforward task, but are surprised to discover how difficult it is. This is true for university students and for trained professionals who perform the task for a living. Recent studies indicate that passport officers, police officers and forensic examiners all show high error rates when engaged in facial comparisons. Using examples, this paper presents an overview of recent efforts to understand and improve facial image comparison in forensic and security settings. Revealingly, intuitions about expertise in facial comparison turn out to be mistaken, and the most promising solution to the problem of identifying unfamiliar faces may be to select individuals with natural aptitude for the task.