Purpose and method. A locus of control (LC) scale was given to a child molester sample before and after treatment for sexual offending. The scale measures the extent to which a person feels that events are contingent on their behaviour or the extent to which they feel events are externally controlled. It was hypothesized that LC would become more internal through treatment and those with a more internal LC prior to treatment would respond better in therapy. The relationship between LC, childhood sexual or physical abuse and offending patterns was also examined. It was hypothesized that victims of abuse would have a more external LC than individuals who had not been abused.Results. It was found that LC became more internal in men who had benefited from treatment and having an internal LC prior to treatment was an important predictor of ‘treatment success’. In contrast, men who did not benefit from treatment either did not change or became more external. Offenders who had been physically abused as children were more externally controlled than those who were not. No difference was found between those who had been sexually victimized and those who were not. External LC was found to be related to higher risk of reconviction for future sexual offending.Conclusions. The findings that there was a significant improvement on LC in men who had responded to treatment, and that having an internal LC prior to treatment was an important predictor of ‘treatment success’, indicate that owning responsibility for actions is an important component of treatment change. This suggests that one of the tasks of treatment with externally controlled men is to encourage them to take responsibility for their behaviour. The finding that it is physical abuse rather than sexual abuse which leads to a more external locus of control may be because sexual abuse victims often report feeling responsible for their abuse. It is likely that this is a function of the messages given by abusers who seek to silence victims by placing blame and responsibility on