Four important health behaviours--dietary fat avoidance, regular exercise, smoking and alcohol consumption--were assessed by questionnaire, together with measures of risk awareness and beliefs about the importance of each behaviour for health, in comparable samples of young adults from eight countries: Belgium, England, Germany, Hungary, Ireland, Poland, Portugal and Spain. Results from 3223 men and 3930 women were analysed. Substantial differences in the prevalence of behaviours were identified, but no country consistently showed the most or least healthy profile across behaviours. Women tended to smoke and drink less than men and attempted to avoid dietary fat to a greater extent, while men exercised more than women. Ratings of the importance of behaviours for health were high, while risk awareness showed wide variations, with lower scores from samples in southern and eastern Europe. Across countries, few associations were observed between the prevalence of behaviour and either mean belief ratings or risk awareness. However, in comparisons of people who did and did not perform each behaviour, beliefs were consistently associated with practice. In multiple regression, beliefs about the importance of the behaviour for health independently accounted for 11.3 per cent of the variance in exercise, 18.9 per cent of the variance in smoking and 4.5 per cent of the variance in alcohol consumption. The association between beliefs and dietary fat avoidance was also substantial. In contrast, the relationships between risk awareness and behaviour were mixed. People who avoided dietary fat were more aware than others of the health risks of fat. But non-smokers were less aware than smokers of the risks of smoking, and people who drank regularly were more aware of the dangers of alcohol than were non-drinkers. The results are discussed in the context of the contribution of health psychology to European health promotion.