The aim of this study was to investigate consumers' decision-making process, attitudes and values towards organic food throughout the employment of the Theory of Planned Behaviour, adapting the methodology from a European project. 450 consumers were interviewed at supermarkets and farmers' markets in Porto Alegre, Brazil. Results indicate a high penetration level and very positive attitude towards organic products. Organics are believed to be healthier, tastier, more natural and environmental friendly, although being less attractive and more expensive than conventional food. Respondents from the farmers' market represent a specific segment whose values are more oriented toward society. The findings showed an alignment between positive attitude and consumption behaviour among the surveyed consumers. The study finally contributes to the stakeholders in general, since the knowledge of the attributes more valued by consumers can help retailers to play the role of coordinators of this supply chain, stimulating producers to adhere to organic certification, helping them to upgrade their production practices and improve their income. Consumers are also benefiting from this offer in the market.