This paper outlines a framework which draws together the currently fragmented understandings of, and actions against, terrorism. The ‘conjunction of terrorist opportunity’ (CTO) stems from a widely known equivalent in crime prevention. Detailed distinctions emerge which clarify the relationship between crime and terrorism. There is special emphasis on historical and higher-level emergent causes, including terrorists' pursuit of strategic objectives and the career of the terrorist organisation itself, as it co-evolves with the society trying to frustrate and destroy it. But the framework seeks to anchor these understandings by reference to terrorist events and their immediate causes. On the basis of this analysis a suite of interventions can then be chosen to match terrorist problem and context and to reflect tactical and strategic priorities. Although the framework is only sketched here, it appears sufficiently promising to test out on a range of case studies by diagnosing causes and describing or suggesting interventions.