The effects of personality and intelligence on economic behaviour in a sample of 207 Scottish farmers were investigated. Data were available on the farmers' attitudes, objectives, and business-related behaviours, together with personality trait and cognitive test scores. Structural equation models of production-oriented business behaviour and environmentally oriented behaviour were constructed. It was found that farmers who score highly on Extraversion (E), Openness to Experience (O), Conscientiousness (C), and cognitive ability are more likely to show production-oriented behaviour and that the effects of personality and cognitive ability are mediated by a more open attitude towards farming. For environmentally oriented behaviour, high scores on E, O, C, and cognitive ability were associated with this behaviour, with mediation by an achievement-oriented attitude to farming, chemical use attitude, and off-farm/diversification objectives; there was also a positive effect of Neuroticism, mediated by pessimistic attitudes to farming and off-farm/diversification objectives. These results show that that personality and intelligence have substantial and measurable effects on farmers' economic behaviour. Copyright © 2001 John Wiley & Sons, Ltd.