In Australia, and other Western countries, there are marked socioeconomic inequalities in mortality from chronic, diet-related diseases. Research in these countries has shown that adults from low socioeconomic backgrounds experience greater morbidity and mortality from these conditions compared to their higher-status counterparts. In recent decades, much research has focused on factors that may contribute to these inequalities. Dietary intakes are thought to account for a large proportion of the socioeconomic variability in health, and there is some evidence suggesting that the psychosocial foundations laid down in adolescence are important influences on these dietary intakes. In Australia, however, existing research examining socioeconomic differences in dietary intakes is limited. Most previous research has looked at dietary intakes in adulthood, and have not considered examining for socioeconomic differences in adolescence. Furthermore, not much is known about the health and nutrition-related beliefs, attitudes and perceptions of adolescents that may contribute to socioeconomic differences in dietary intakes. This study examined these issues by analysing for socioeconomic differences in food and nutrient intakes among both adolescents and adults. It also investigated some health and nutrition-related beliefs, attitudes and perceptions of adolescents from different socioeconomic backgrounds. Data from a national cross-sectional survey, the 1995 Australian National Nutrition Survey, were analysed to determine socioeconomic differences in food and nutrient intakes. Qualitative interviews were undertaken with adolescents to investigate their health and nutrition-related beliefs, attitudes and perceptions. The results show that compared to adults, there is less socioeconomic inequality in food and nutrient intakes among adolescents. Intakes of some anti-oxidant vitamins and folate were directly related with socioeconomic position among adults. Adults from low socioeconomic backgrounds were less likely to consume fruits or vegetables. They consumed a lower variety of fruits and vegetables and were less likely to choose fruits and vegetables high in vitamin A, folate and vitamin C. The results showed that these differences may be due to adults from low socioeconomic backgrounds being less likely to want to increase their fruit and vegetable intakes, and perceiving price and storage as barriers to doing so. There were a small number of socioeconomic differences in adolescents' beliefs, attitudes and perceptions about nutrition and health that may contribute to dietary intake inequalities in adulthood. Adolescents from lower socioeconomic backgrounds were less likely to see health as being important for achieving goals, and identified nutrients and sleep as influencing their health less frequently. These adolescents also referred to dietary recommendations, nutrient intakes, dairy foods and avoiding school canteen foods less frequently when describing a healthy diet. A number of recommendations about the design and targeting of nutrition-promotion campaigns and interventions are discussed, as well as future directions for research on socioeconomic differences in dietary intakes.