Psychopathy, which is related to antisocial personality disorder, is most prevalent in criminal offender populations and is a major risk factor for criminal recidivism, particularly violent criminal recidivism. The current study draws on Loevinger’s theory of ego development to assess whether inmates who fall into the category of low ego development based on their sentence completion scores also score high on the Psychopathy Checklist-Revised (PCL-R). Participants were 76 male inmates in a high-security prison in Germany who completed a sentence completion test (SCT) developed by the author, which contained 23 content and linguistic categories derived from Loevinger’s theory of ego development. Clinical interviews were conducted and the PCL-R was scored for each participant. Results of statistical analyses indicated moderate correlations between PCL-R scores and the cognitive and linguistic characteristics in the SCT. However, while these characteristics were highly sensitive, they were not specific to psychopaths. As such, the SCT is not a valid assessment tool for psychopathy. However, verbal patterns, coupled with interpersonal behavior patterns and linguistic properties, may be useful indicators of psychopathy when other information is lacking. Future research should focus on identifying additional diagnostic criteria and refining current criteria to make scoring of the SCT more reliable. Tables, figures, references