PurposeThis study focused upon whether outcome following Enhanced Thinking Skills (ETS) groups for incarcerated offenders could be predicted by the offenders' pre-training levels of executive function. It also addressed whether this predictive function was above and beyond that predicted by intelligence, demographic information, conviction history, emotional distress and social compliance. MethodsOffenders due to undergo ETS were assessed using a battery of neuropsychological measures of executive functioning and other psychometric instruments. Change in behaviour following ETS was assessed using the Behaviour Rating Scale (BRS). The results of this assessment were entered into regression analyses, with the post-ETS changes in the positive and negative scales of the BRS as the independent variables in 2 separate analyses. ResultsAspects of executive functioning related to attentional set shifting ability were found to be highly predictive of outcome, with those with relatively weaker executive functioning showing the most improvement. Participant age and number of previous convictions were found to be predictive of reductions in negative behaviour but not of improvements in positive behaviour, with older participants and those with more previous convictions showing the greatest degree of improvement. ConclusionsETS can be of particular benefit to those offenders with relatively poor executive functioning.