Nineteen teachers took part in a brief, one session, in-service course in which they were trained in behavioural techniques with the main aim of helping them increase their rates of approval contingent upon required behaviours from their pupils and to decrease their rates of disapproval. Subsidiary aims were that the teachers would be enabled to alter the balance of approval/disapproval given to academic and social behaviours, to increase the rate of approval given to group behaviours, to increase the rate of description given to behaviours approved/disapproved, to use pupils' names more frequently and increase redirections given to behaviours following disapproval. From observations taken before and after training, it was seen that the main aim was achieved, with teachers showing increased levels of approval contingent upon required behaviour and decreased levels of disapproval, these changes being accompanied by increased pupil on-task behaviour. For the subsidiary aims, the data showed an encouraging shift in the balance of the teachers' verbal behaviour towards social and academic behaviours but the results were rather mixed for the other subsidiary aims.