One important aim of the Swedish Action Programme for Nutrition is to increase the consumption of dietary fibre and decrease fat intake. The currently available extensive range of fat-reduced and fibre-enriched foods makes these dietary practices possible, but also makes the selection of a health promoting diet more complex. This thesis aims to contribute to the understanding of psychosocial influences on schoolchildren?s food choice, with specific attention to fat and fibre content. The focus was on breakfast because typical Swedish breakfast foods are important sources of fat and fibre. The Theory of Planned Behaviour formed the theoretical basis of the studies. All pupils in the 5th, 7th and 9th grades in M?lndal municipality (N=1730) were asked to complete a questionnaire and a 7-day food record. Interviews were performed with 181 of those subjects. A picture-sort interview technique, the ?stacking box methodology?, was employed to describe perceptions and habitual choices. Assessing diets of children and adolescents is not an easy task. As in all dietary surveys, reporting and participation biases may exist. The present study using food records illustrates several such biases, which should be taken into consideration in the design, analysis and interpretation of future studies. The ?stacking box methodology? seems promising, and appeared to have some advantages compared to traditional methods. However, the two dietary assessment methods generally yielded similar results. Reduced-fat choices of milk and margarine were common, although a considerable number of subjects consumed full-fat products. When it comes to the consumption of bread and cereals, the low-fibre alternatives dominated. At the age of 11 as well as 15, children?s own attitudes and underlying beliefs were of importance for breakfast food choices, as was parental influence. Parents influenced food choice by controlling food availability, acting as models and encouraging the child to consume. The perceived parental norms supported dietary changes towards products with more fibre but not towards fat-reduced products. However, the perception of parents? own consumption seemed to favour consumption of fat-reduced milk. Participants? attitudes were associated with health beliefs as well as taste perceptions. In general, the results suggest that taste may be a barrier to the consumption of high-fibre products, while consumption of low-fat products appears to be impeded by health beliefs. Contrary to several other studies, the present results suggest that some aspects of young people?s dietary behaviour are related to their knowledge. Specifically, the choice of high-fibre products was associated with knowledge of fibre sources and the choice of fat-reduced milk products was associated with a positive attitude towards limited fat intake.