This paper investigates whether norms guiding environmentally desirable behaviour are genuinely internalized and integrated into the person's cognitive and goal structures or just shallowly "introjected" social norms. Internet-based questionnaires were administered to a stratified sample of Danish consumers (N = 206). Each questionnaire contained standard items measuring subjective social and personal norms for the purchase of organic food, self-reported buying behaviour, and a "hard laddering" instrument probing reasons and motives for doing so. As expected, participants' means-end associations to the studied behaviour differ significantly depending on the strength of their norms and the two types of norms differ in their embeddedness in the person's cognitive structures. The behavioural influence of subjective social norms and expressed reasons and motives is mediated through personal norms. The results are consistent with the analyzed behaviour being guided by truly internalized and integrated (personal) norms.