This study using a prison sample to explore Social Dominance Orientation (SDO), socially dominant inmate behavior, index offence, age and length of time served in secure environments. A sample of 397 adult male prisoners completed the Direct and Indirect Prisoner Behavior Checklist- Scaled (prisoner behavior towards other inmates and staff) and the Social Dominance Orientation (SDO) Scale. It was predicted that prisoners would report higher SDO than non-incarcerated populations and that among inmates those with approach orientated index offences would be higher in SDO than those whose offenses were more remote. It was also predicted that SDO would be related to younger age, higher lifetime rates of incarceration, more negative behavior towards other inmates and staff, and more resource focused behavior. The results broadly supported predictions, and possible implications for practice and directions for future research are discussed. (Published Abstract)