This paper analyses the transformation of Irish economic policy formulation from the formation of the first inter-party government in 1948 to the breakdown of Ireland's application to join the EEC in 1963. It shows that the influence of trade unions, employers' groups and farmers' organisations on policy making in the period marked the inception of a corporatist style approach to national policy making. This period saw a general evolution in the process of the formulation of public policy towards a more conscious and overt tripartite set of arrangements. There was a gradual maturation of relations between the emerging interest groups and the government in the policy realm. The formalisation of these interest groups wherein they played a role in the long term policy planning process is emphasised. While their various representatives made strenuous efforts to advance their members' sectional interests, all groups were able to take a strikingly dispassionate and long term view of the country's economic prospects. This paper stresses the importance of Sean Lemass both in opposition and in government and argues that he was the key player in moving the country from a policy of protectionism to one where interdependence with other economies was assumed. By pointing out explicitly to the various economic actors in the Irish body politic that ideological change was needed in the formulation of economic policy, the Fianna Fail government of 1957-1961 was able to set out a concrete agenda for the development of the Irish economy by the early 1960s. Export-led industrialisation and economic co-operation with Europe were at the heart of theses new methods. Ultimately Irish economic policy formulation had moved dramatically in an ideological sense in the fifteen years since 1948: the new ideology was a formalised proto corporatist style social democracy which involved all the key players collectively in responsible decision making.