Changes in locus of control and self-esteem during social skills training and at 6 month follow-up were investigated. Forty-four adolescent, male offenders were randomly assigned to a social skills training, attention-placebo, or no-treatment control procedure. The results showed that pre- to post-training increases in self-esteem were produced for both the social skills training and attention-placebo control groups, but not for the no-treatment control group. These increases did not continue during the follow-up phase; the social skills training group, which showed the greatest improvement during training, displayed a decrease in self- esteem during follow-up. The locus of control measures showed a statistically significant shift towards internality for the social skills training group during training, which was not found for the attention-placebo and no-treatment controls. During the follow-up phase, all three groups showed a statistically significant shift towards externality, suggesting a tendency for boys to view their behaviour and consequences as being under the control of chance factors or powerful others, during institutionalization. This effect was partly reversed during training for the social skills training group, but the effect was not long lasting. It seems therefore that social skills training is effective in producing an increase in self-esteem and a shift towards internal locus of control. These changes are, however, of short duration and the self-esteem shift may be the result of increased staff contact or other non-specific therapy factors.