The creation of devolved institutions in Scotland and Wales in 1999 provided nationalist parties in both the opportunity to act within an institution solely within their nation’s territorial boundaries. In 2007, they entered government for the first time. In so doing, the Scottish National Party and Plaid Cymru embarked upon public engagement strategies in office which were designed to build support for their constitutional ambitions – namely, independence for Scotland and (in the short-term) full legislative powers for the National Assembly for Wales, as outlined in the Government of Wales Act 2006. This thesis explores the public engagement strategy of both parties, focusing on the respective consultations of the parties in government – A National Conversation and the All Wales Convention¬ – and the following campaign for (in Scotland) and at (in Wales) a referendum intended to deliver their preferred outcome. The aim of this thesis is to consider why public engagement strategies were considered the best vehicle to take forward the respective parties’ constitutional goals and to evaluate the success each party achieved in relation to these objectives. This thesis argues that, while both the SNP and Plaid Cymru have achieved some success with regard to their constitutional objectives, this success can be measured differently depending whether short-term or long-term goals are the defining standard. In Wales, Plaid Cymru’s constitutional consultation found limited engagement with the wider Welsh population, and though the referendum succeeded in securing legislative powers for the National Assembly for Wales, public engagement with the constitutional debate in Wales continues to lack enthusiasm. By contrast, the SNP’s National Conversation saw more enthusiastic engagement, but without a referendum at the end of the process, a clear lack of a tangible short-term outcome. However, the SNP in government did succeed in moving the constitutional debate firmly onto the political agenda, and engagement in this debate is now widespread in Scottish society, particularly in the wake of an agreement to hold an independence referendum in autumn 2014.