This is a mixed methods study. The data are an output from an ESRC-funded comparative project on Devolution and Decentralisation in Wales and Brittany, part of the ESRC’s Devolution and Constitutional Change programme. The project set out with several objectives: to compare public opinion about political institutions and public policy in Wales and the French region of Brittany; to compare and contrast mass and elite opinions on institutions and policy within and across Wales and Brittany; to inform policy practice in Wales by drawing lessons from experience in Brittany (especially in the fields of regional languages, education and training) and to contribute to our knowledge of European regional governance by adopting a comparative perspective and elaborating new theoretical frameworks. Around 200 face-to-face interviews were conducted in Wales and Brittany as well as a Welsh language focus group, a comparative opinion survey, and an elite questionnaire in four languages (English, Welsh, French and Breton). The data for Political Institutions, Public Policy and Public Opinion in Brittany, France, 2001 and Political Institutions, Public Policy and Public Opinion in Wales, 2001 also provides information from the opinion poll carried out in Brittany and Wales in June 2001. The market research companies interviewed a representative sample of individuals, selected by quotas of age, gender, socio-economic group and locality. Interviews were conducted by telephone, using CATI. The data for Political Institutions, Public Policy and the Policy Community in Brittany, France, 2001-2002 (elite survey) and Political Institutions, Public Policy and the Policy Community in Wales, 2001-2002 (elite survey) provides information from the elite survey conducted in Brittany and Wales in 2001 and 2002. The questionnaire was distributed to members of the policy community. The data for Regional Governance and the Policy Community in Brittany, France, 2001-2002 and Devolution and the Policy Community in Wales, 2001-2002 provides transcripts and summaries of interviews conducted in Brittany and Wales during 2001 and 2002. The interview sample for the 'policy community' data were determined by snowball sampling and advice from members of an advisory group. Public Opinion and Policy Community data for Wales and Brittany The socio-demographic variables are those of region; locality; gender; occupation of chief income earner; level of education; country of birth; intended vote in a general election; intended vote in an Assembly election (Wales)/ Regional Council election (Brittany); working status; time spent in Wales/Brittany; age; marital status; children in full time education and level of interest in politics. Most of the survey material is in the form of detailed analysis of attitudinal and opinion variables on matters relating to devolution/decentralisation; Welsh/Breton identity and attitudes (preferences) towards issues of the Welsh/Breton language; education and training. The principal attitudinal questions investigate views on devolution/decentralisation for Wales/Brittany; the 'Moreno' identity scale; the Loire-Atlantique and administrative region of Brittany; opinions and views on the performance of the National Assembly/Brittany Regional Council; beliefs about the main challenges facing Wales; future expenditure priorities; preferences for regional political institutions; relations between the Assembly/Regional Council and similar bodies elsewhere in Europe; importance of organisations and levels of government for the governance of Wales/Brittany; understanding of, and views om, the Welsh/Breton language; public policy and decision-making arenas and the Welsh/Breton language; lessons from linguistic experiences elsewhere; Breton language in schools; attendance at a training course in the past 24 months; priorities for spending money on training in Wales/Brittany; decision-making arenas and training in Wales/Brittany; priorities for improving the training of young people and attitudes towards adopting more interventionist policies (the importance of qualifications against employment, the desirability of training levies and whether there should be a legal requirement to undertake training); lessons from experiences elsewhere. Regional Governance and the Policy Community in Brittany Interviews The data consists of a rich archive of 67 interview transcriptions. Prolonged face-to-face interviews took place during two separate periods of six months in France, from April to September 2001 and 2002. Interviews were taped and transcribed. They lasted an average of one hour.