With the aid of a theoretically-based analysis of four historical and four current change processes - or transition case studies - in agriculture, we have made a study of how farmers and their associated actors move towards a sustainable agriculture. The change processes always appear to need the same 'conditions' in order to be successful and also appear always to encounter the same types of obstacles. It may be concluded from this that better advance anticipation of obstacles' hanging above the heads' of people involved in change needs to be possible, so that the envisaged change processes can proceed more easily. It remains a fact, however, that every change process also encounters unmanageable, unpredictable obstacles.