Whole grain consumption is associated with reduced risk of chronic disease. One-fifth of UK adults and children do not consume any whole grains, and adolescents have low consumption rates. Factors affecting whole grain intake among adolescents are not well understood. This study examined the socio-economic, environmental, lifestyle and psychological factors likely to influence consumption and explored whether outcomes aligned with behavioural predictors proposed in the Reasoned Action Approach. Five focus groups explored young people's attitudes towards, knowledge and consumption of wholegrain foods, as well as barriers to, and facilitators of, consumption. Participants were male and female adolescents (n = 50) aged 11–16 years from mixed socioeconomic backgrounds and ethnicities, recruited through schools in the city of Leeds, UK. Focus groups were analysed using thematic analysis. Most participants had tried wholegrain food products, with cereal products being the most popular. Many recognised whole grain health benefits related to digestive health but not those related to heart disease or cancers. Several barriers to eating whole grains were identified including: difficulties in identifying wholegrain products and their health benefits; taste and visual appeal; and poor availability outside the home. Suggested facilitators of consumption were advertisements and educational campaigns, followed by improved sensory appeal, increased availability and choice, and tailoring products for young people. All constructs of the Theory of Reasoned Action were identifiable in the data, suggesting that the factors influencing whole grain intake in adolescents are well captured by this model. Study outcomes may inform research and health promotion to increase whole grain intake in this age group.