For more than twenty years now European agricultural policies have been striving, among other things, to support environment-friendly agriculture able to protect the natural landscape and contribute to the multifunctional development of rural areas. Assistance programmes designed to support various agricultural-environmental ventures, organic farming included, are based on the voluntary participation of farmers. From the point of view of the effectiveness of such programmes factors that encourage farmers to participate in their implementation are important. Studies have revealed a number of such factors, including those that characterize the assistance programmes themselves, the farmers (their code of values and their attitudes), the farms and external conditions. However, an analysis of the results of conducted research has not indicated in a clear way which of these factors are decisive for the change of methods of running a farm. In addition, the effectiveness of programmes addressed to farmers is understood not only in a behavioural way but also as a mental change. Dynamic models, which relate to the changes in mentality and attitudes, and the theory of innovation make it possible to explain some inconsistencies in the results of research concerning factors essential for the change in the methods of running a farm. It seems that factors which play an important role in Poland include: uncertainty stemming from the instability of policies, which is utilised by farmers at the time of taking decisions, and a cascading effect brought about by the appearance of effective actions in the situation of uncertainty.