This article argues that criminal and deviant behaviour can be productively viewed through an action system framework. The idea is developed by considering two forms of destructive behaviour: arson and barricade-hostage terrorist incidents. Two studies are presented. The first study tests the hypothesis that different forms of arson will reflect the four dominant states that an action system can take; integrative, expressive, conservative, and adaptive. A smallest space analysis was performed on 46 variables describing 230 cases of arson and the results identified the four themes of action system functioning. An examination of the personal characteristics of the arsonists also produced four variable groupings and a combined analysis of the four action scales and four characteristics scales also supported the structural hypothesis of the action system model. The second study applied the action system model to the study acts of terrorist barricade-hostage incidents. A smallest space analysis of 44 variables coded from 41 incidents again revealed four distinct forms of activity, which were psychologically similar to the four modes of arson identified in study one. Overall, these two studies provide support for the appropriateness of the action system framework as a way of classifying different forms of deviant behaviour.