In the 1980s a number of measures were introduced in order to curb the growing problem of surpluses in production in many sectors of European agriculture. In responding to these measures, farmers have had to reconsider questions of enterprise choice and levels of specialisation in their farming operations. This paper examines the resultant regional patterns of enterprise substitution which have occurred in Ireland. It is demonstrated that, while there has been some continuity between the 1980s and previous decades in relation to intensification processes, there has been a reversal of the trend towards greater regional specialisation, so that by the end of the 1980s the production system in each region was more diversified. Shift and share analysis is used to disaggregate the components of change for each region.