Criminal sentiments are the highest risk factor for recidivism. Although criminal sentiments have been reliably measured, there are few scales measuring violent sentiments. The aim of this study was to report on three studies exploring the theory and psychometrics of a new Justification for Violence Scale (JFV). The JFV items have high ecological validity in that they were drawn from in-depth interviews with violent men. Psychometric analysis showed that the JFV was unifactorial with high criterion-related validity differentiating three distinct groups (sample N=530): male offenders, men and women from the community, and university undergraduates. In a further study of 250 community adults, high correlations with self-reported physical aggression and violent fantasies, and negative correlations with social desirability supported the JFV's convergent and discriminant validity. The JFV can be used by researchers or clinicians as a single measure or the items can be inserted into the Criminal Sentiments Scale to enhance the measurement of violent and criminal attitudes and beliefs.