Abstract
In order to chance the driving behavior of mailvan-drivers so as to encourage energy saving, a programme was developed and carried out in the Netherlands Postal and Telecommunications Services (PTT). The design of this programme was based on a careful analysis of driving behavior in the same organization. From four angles of approach driving behavior has been influenced. The results of the programme were most satisfactory. Compared with a control-group, attitudes, social norms, and reported behavior have changed as desired. Energy savings of over seven percent were achieved.