This thesis provides a description and analysis of government intervention in the Welsh economy between 1974 and 1997. During this period, Wales underwent rapid and far-reaching economic upheaval on such a massive scale that few avoided its impact. The scale of these changes was dramatic, as was the intensity of attempts to deal with their consequences. Wales acted as a laboratory for the development of approaches to government intervention in the economy. This thesis defines government intervention in the Welsh economy, before identifying activity, expenditure and (where possible) outputs across categories including land reclamation, factory construction, attraction of foreign direct investment, urban renewal, business support and the provision of grants and subsidies. It also places such interventions in their political and economic contexts, highlighting the dynamics that evolved between policies developed in Cardiff and London. By doing this, it asks and answers three questions relating to the changing dynamics of government intervention; namely, what was done, why was it done and was it effective? The thesis draws on primary sources including interviews with politicians and those formerly holding senior positions within governmental organisations, records held by the National Archives, personal and organisational archives held by the National Library of Wales, records held by other archives, newspapers and government publications. Secondary texts are discussed and drawn upon, with this study adding a history of government intervention in the Welsh economy to the literature for the first time.