A study was conducted to examine three proposed underlying factors in criminal behaviour; childhood maltreatment, personality type and aggression. Two groups of participants were asked to volunteer. Firstly, an experimental group, consisting of 44 convicted offenders, and secondly, a control group, 44 individuals with no previous convictions. All participants were given the same questionnaire booklet which included a copy of the Childhood Trauma Questionnaire (CTQ), the Framingham Anger Scales and the Framingham Type A Scale (FTAS). These questionnaires examined each of the above factors and the data collected was analyzed using SPSS. It was predicted that there would be a significant difference in participant's score of each factor depending on whether they were in the experimental or control group. Two predictions, concerning childhood abuse/neglect and aggression were partially supported. Results for personality type were not significant and the null hypoFinal Year Project was retained. Anger symptoms were found to be significantly and positively correlated with all forms of childhood abuse and neglect. These results are discussed in terms of how they can further our understanding of criminal behaviour, with a view to understanding the practical implications for treatment. Some methodological issues are raised and proposals for future research are highlighted.