Approaches to assessing violence in clinical practice have been influenced by developments in the field of risk assessment. As a result, there has been a focus on identifying and describing factors associated with violence. However, a factor-based approach to assessing violence in individual cases has limited clinical utility. In response, the benefits of a formulation-based approach have been promoted. This approach is enhanced by an understanding of the specific mental mechanisms that increase the likelihood of violence in the individual case. Although there is an empirical evidence base for mental mechanisms associated with violence, this literature has not been distilled and synthesised in a way that informs routine clinical practice. In this article the authors present the key mechanisms that are known to be associated with violence in a way that is relevant to the clinical assessment of violence and, in turn, can inform clinical and risk management.