The key to health promotion and disease prevention in the 21st century is to establish an environment that supports positive health behaviour and healthy lifestyle from childhood. The HELENA project includes cross-sectional, crossover and pilot community intervention multi-centre studies, as an integrated approach to the above-mentioned problem. Dietary intake, nutrition knowledge and eating attitudes, food choices and preferences, body composition, biochemical, physical activity and fitness and genotype (to analyse gene-nutrient and gene-environment interactions) assessment will provide the full information about the nutritional and lifestyle status of the European adolescents. The requirements for health promoting foods will be also identified, and three sensory acceptable products for adolescents will be developed. Harmonization and standardisation of the assessments for both scientific and technological objectives should result in reliable and comparable data of a representative sample of European adolescents. This will contribute to understand why health-related messages are not being as effective as expected in the adolescent population. A realistic intervention strategy will be proposed in order to achieve the goals of understanding and effectively enhancing nutritional and lifestyle habits of adolescents in Europe.