A total of 200 adult male inmates incarcerated for various offenses at the Federal Correctional Institution, Lompoc, Calif,. were randomly selected as subjects. The subjects' MMPI scores were classified according to the Megargee typology. The subjects were than divided into violence-prone and nonviolence-prone groups. The two groups were compared on the following variables: (1) violent or nonviolent conviction offense, (2) violent acts committed during incarceration as evidenced by incident reports, (3) number of prior arrests, and (4) number of prior prison commitments. Inmates in the violence-prone group according to Megargee's typology did not have proportionately more prior convictions than those in the nonviolent group. Further, those in the violence-prone group did not commit proportionately more violent acts during incarceration than did the nonviolence-prone group. Other variables significant to violence during incarceration were age and violent conviction offenses. Inmates who committed violent acts during incarceration were significantly younger than those who did not. An inmate's past violent behavior is apparently a better predictor of violent behavior during incarceration than the Megargee typology. In examining the individual scales of the MMPI related to whether an inmate committed a violent act during incarceration, significant differences were in four scales: Frequency, Hysteria, Psychasthenia, and Schizophrenia. Results are discussed in relation to recent literature, ehtical considerations, and implications for future research. Tabular data, 2 notes, and 74 references are provided. (Author abstract modified)