This study examines the relationship between-farmers' motivation, as measured by orientation to work, and their adoption of new farm practices. Reviews of New Zealand agricultural extension research, of well-known motivation theories and of research into farmers' motivation are presented. A model which relates variables assessing the farmer's situation, experience, orientation to work, practice adoption and the level of farm performance which he achieves is developed. The relationships described in the model were tested using data gathered in a personal interview survey of 90 full-time sheep farmers in Oxford County, New Zealand. Orientation to work was measured with a projective questioning technique and ten Likert scales constructed from the responses to 55 attitude statements. Orientations towards increasing income, intrinsic aspects of farming, less work, social aspects of farming and achievement were identified with the projective technique. Orientation to work was found to be associated with practice adoption. Farmers who emphasised increasing income, achievement, risk or future orientations were earlier adopters of practices than those who emphasised social, intrinsic, self-esteem or fatalism orientations. A more important determinant of farmers' practice adoption decisions than orientation to work was their knowledge of the practice. Many farmers had accepted incomplete or inaccurate information about the practices studied, and believed that the costs of adoption outweighed the benefits. Three situational variables (level of debt, age and management ability) and two measures of farmers' experience (education and years of farming experience) were consistently associated with orientation to work. Measures of farm performance were associated with farm size and with farmers' management ability but not with practice adoption or with the farmer's perception of the adequacy of his income or with his satisfaction. This can be attributed to the limited reliability of the measurement techniques used. It is concluded that the proposed model provides a reasonable description of the relationships between orientation to work and other factors. Some refinements to the model are also suggested. The study has several implications for extension practice in New Zealand. The most significant of these is that extension officers who are dissatisfied with farmers' levels of practice adoption should attempt to communicate more effectively with farmers and in most cases should not attribute the failure to adopt new practices to a lack of motivation.