The purpose of this study was (1) to examine the structure of attitudes towards healthy food in a group of adolescents and (2) to evaluate the impact of a health education programme on these attitudes. The strategy used was to make 14-year-old schoolchildren learn about nutrition and dental health by teaching these topics to 10-year-old children. A pre-test/post-test non-equivalent control group design was used. The experimental group consisted of four classes of 14-year-old children from two schools and the reference group of four classes of the same age from two comparable schools. The data were collected prior to, immediately after, and, for the experimental group, two months after the implementation of the programme. Factor analysis revealed three dimensions of attitudes: PROHEALTH, TASTE, and SIGNIFICANT OTHERS. Analysis of covariance with pre-test measures as covariates showed a significant effect of the programme on PROHEALTH, no effect on TASTE, and a significant study group by gender interaction effect on SIGNIFICANT OTHERS, which, however, was impaired two months later. It is concluded that the change in attitudes can be explained by two mechanisms: dissonance arousal and discrepancy between personal attitudes and group norms; and that future programmes should emphasise affection rather than cognition.