Computer-technology has led to the use of new principles of persuasion. These new principles constitute the unique working mechanisms of persuasion by means of computer. In the present study, three tailored messages that each contained one potential working mechanism - personalization, adaptation or feedback - were compared with a standard information condition. Two hundred and two students who smoked tobacco daily were randomly divided over four conditions. After the computer pre-test questionnaire, they read the information in their condition and filled in the immediate post-test. After 4 months, they were sent a follow-up questionnaire assessing their quitting activity. The data show that personalization (44.5%) and feedback (48.7%) but not adaptation (28.6%) led to significantly more quitting activity after 4 months than did the standard information (22.9%). Moreover, the effect of condition on quitting activity was mediated by individuals' evaluations of the extent to which the information took into account personal characteristics.