The study emanates from the need to explore and gain insight into the factors that led to the criminal behaviour of persons with mental disorders who are admitted to Lobatse Mental Hospital following a criminal offence. Objectives of the study were to provide a broad theoretical background on criminality amongst persons with mental disorders; to explore factors that contribute to the criminal behaviour of persons with mental disorders; and lastly, to draw conclusions and recommendations regarding reduction of criminal behaviour amongst persons with mental disorders. The study utilised and answered a research question that read as follows: What are the contributing factors to the criminal behaviour of persons with mental disorders? The study was therefore centred on this question as it was undertaken to find answers to the research question. The study used qualitative research approach because the researcher heavily relied on subjective data provided by the small sample, which in turn has been used to generate some understanding of the factors contributing to the criminal behaviour of persons with mental disorders. Applied research was used because it addresses the problem of criminal behaviour of persons with mental disorders and draws conclusions and recommendations to the reduction of the criminal behaviour amongst persons with mental disorders. The study also followed a qualitative research approach, in particular a collective case study strategy. The population for this study comprised of all offenders with mental disorders at Lobatse Mental Hospital. The researcher relied on purposive sampling technique to select the participants. Twelve patients with a mental disorder admitted at Lobatse Mental Hospital were interviewed face-to-face by the researcher and a tape recorder was used to capture the data. In analyzing the data themes that were categorised in line with emerging patterns, particularly with reference to the research question, were identified. The conclusion from the literature review revealed that there is a causal relationship between mental disorders and criminal behaviour. It however revealed that persons with mental disorders with psychotic symptoms are at increased risk of criminal behaviour. Literature also showed that persons with mental disorders can commit crimes not necessarily due to their mental disorder but to other factors such as greed, lack of conscience and revenge. The factors contributing to the criminal behaviour of persons with mental disorders as revealed by the participants are as follows: mental disorder accompanied by psychotic symptoms; alcohol and substance abuse; male; single; lower educational achievement; unemployed; self defence; mixing traditional and modern medicine; treatment non-adherence; poor interpersonal relationships with significant others; delay in seeking appropriate treatment; lack of education on one mental condition; living alone without anyone to monitor the signs and symptoms of the mental condition; poor conflict resolution skills. Copyright / Dissertation (MSW)--University of Pretoria, 2009. / Social Work and Criminology / unrestricted