Twenty-four Canadian laypersons and 24 clinicians each evaluated 4 fictitious case histories involving a theft, an armed robbery, a murder, and an attempted suicide. Half the subjects read case histories designed to lead to the conclusion that the offender's action resulted from internal forces and was consistent with the offender's character. The other half read case histories designed to suggest that causality resulted from immediate environmental provocation and other external factors. Laypersons and clinicians tended to agree. Offenders whose actions were regarded as internally caused were regarded as more dangerous and less likely to benefit from treatment than were offenders in the external classification. Offenders' perceived treatability was negatively related to perceived dangerousness. Results supported the application of attribution theory to clinical judgment and also supported the view that, with respect to offenders with personality disorders, treatment decisions are made on the basis of commonsense criteria. Data tables, figure, and 14 references. (Author abstract modified)