Linkage problems are formulated in terms of the problematic relationships between, on the one hand, the provision of educational and public information programmes, and, on the other hand, the use made by adults of these programmes. In the meantime, the research programme has devoted increasing attention to linkage problems in terms of the characteristics of educational and public information programmes themselves as contributing to their success and failure in reaching their intended audiences. Theoretical perspectives from the educational and other social sciences provide the basis for research into both the historical and contemporary manifestations of linkage problems in the social and cultural sector with particular reference to the areas of adult education and public information.
Comparative research is an increasingly important dimension of the programme.
Another feature is the emphasis upon empirical research, with use of both quantitative and qualitative methodologies, which contributes to the growth of the body of knowledge and the development of theoretical formulations of linkage problems. Overview of scientific results Since 1982, the historical research of the Centre has been concentrated on the contribution of social movements and voluntary organizations to the development of adult education, including public information, in the Netherlands, and more recently, in other European countries. The period 1890-1930 has been frequently considered as the most formative episode. In this connection, members of the Leiden staff have examined the development of adult education in the women's and trade union movements and the role of voluntary organizations in the founding of folk houses, folk universities, folk high schools and public libraries. Time and again, the influence of British examples such as 'university settlement' and 'university extension' was found to be essential.