The aim of this research is to explore the question of how farmers learn, in constructing knowledge both in and for practice. It seeks to identify how they gain new ideas, make changes, develop to a level of expertise and who and what contribute to this process. The rapidity of change in a high tech environment, combined with globalisation, the new economy and the knowledge age, means that farmers are living their lives in 'fast forward' mode. There is so much new technology, research and development available that the ability to identify information relevant to a particular farming practice and to process it to knowledge is an increasing challenge. Six central South Island (N.Z.) farmers were selected purposively as case studies. The range of case profiles provides for comparison and contrast of the relative importance of formal qualifications, differences between sheep/beef farmers and dairy farmers, levels of expertise, age and experiences. The self-rating of the farmers enables a comparison of lower and higher performers, identifying characteristics which enable insight into why some farmers consistently lead new practice and why others are reluctant followers. The research is qualitative in design and approached from a constructlVIst and interpretive paradigm. Socially and experientially based, it seeks to understand the experiences of the subjects through in-depth interviews and observations. This study identifies farmers as social learners although working independently, in relative geographical isolation and often, social isolation. It concludes that these farmers learn through participation in the practice of farming. This practice includes a constellation of cOmInunities of practice, which may be resource-rich or resource-poor, depending on the range and depth of the farmer's involvement. Through full and committed participation in these practice communities and associate constellations, the practitioner's identity evolves, encouraging new practices, ideas and innovation. This study emphasises that expertise is not a permanent state but requires evolving identity, knowledge and dispositional ability; for maintenance and growth within a culture of practice. Emergent grounded theory suggests that dispositional knowledge underpins construction and use of all knowledge; that construction and use of high-order propositional and procedural knowledge requires higher-order dispositional knowledge and that mastery is developed through evolving identity, dispositions, leadership and learning, socioculturally constructed through resource-rich constellations of communities of practice.