There are numerous reasons why land users do not always adopt innovations even though all evidence may suggest that they should. The purpose of this study was to review the literature in the field of extension and technology transfer drawing upon the rural sector primarily in Australia. Australia is now recognized as a world leader in adopting new technology and ideas, particularly those relating to the management of the physical environment but there has been little assessment of the circumstances and constraints surrounding this adoption. The reasons for non-adoption range from complexity of the technology, land user's beliefs and opinions towards the innovation, attitude to risk and conflicting information. For different land-use enterprises and innovations, different constraints will apply and it is argued that these are in three broad categories, characterized by: the land user and the adoption process; the characteristics of, and issues associated with the developers of, the innovation; and the role of extension agents and the transfer process. It is apparent from the changing nature of technology transfer that commercial organizations have assumed a leading role in this field and land users are being recognized as key stakeholders in both the adoption and technology development processes. The study, however, reveals a shortage of data on the effectiveness of corporations and other commercial organizations in the technology transfer and adoption processes.