This paper contains the reflections of the first author as a forensic psychologist working with convicted terrorists in prison between 2008 and 2011, and subsequently as an academic and government consultant in this field. The task of making sense of this learning has been helped by a psychoanalytic understanding of the causes of terrorism by the second author who is a psychotherapist and group analyst. Psychoanalytic processes of defences, splitting and projection throw light on the potential unconscious thoughts, feelings and behaviour of those who resort to terrorism. Two broad groups are identified whose motivations are ostensibly noble cause and criminality respectively, but whose involvement also serves to avenge their personal humiliations and feelings of injustice that are projected into a political cause. A third group is also described of mainly lone actors motivated by pathological narcissism. It is proposed that terrorism manifests as a political phenomenon but is also a form of communication that reveals much about the state of mind of those who choose to become involved.