Certified organic production by small-scale farmers in developing countries is increasingly promoted as an opportunity to access a growing and dynamic market, while at the same time, enhance productivity and improve incomes. Nevertheless, adoption has been limited. The economics literature suggests profitability is the main constraint, however, the sustainable agriculture literature is inconclusive and considers attitudes of significant importance. Using the Theory of Planned Behaviour, this study investigates the psychological barriers to adoption using small-scale avocado producers from Michoacan, Mexico as a case study. The data is obtained from a household study carried out during 2004 and is modelled using an ordered probit model. Despite positive attitudes towards organic production, intentions to convert are negative. Intentions are significantly influenced by social pressures (subjective norm) and the perceived ability to successfully convert to organic production. Promotion of organic production will therefore require a focus on information asymmetries within the wider population, development of technical skills, the alleviation of credit constraints and the creation of an enabling environment.