The purpose of this study was first to assess and then to improve the diet of Greek primary school children teaching them healthy dietary habits and instructing them to face critically advertisements and media projected dietary models using a program which included intervention on cognitive, emotional, and social level. The results show that our intervention was more effective on the cognitive level and in particular on children's ability to estimate the dietary value of different kinds of food. However, their food preferences were not affected significantly, suggesting that these are more resistant to change since they are already consolidated and, therefore, need longer intervention.