The Central Archive archives primary material (data, questionnaires, code plans) and results of empirical studies in order to prepare them for secondary analyses and to make them available to the interested public. The range of the ZA encompasses all technical areas in which procedures of empirical and historical social research are used. This site offers general information about the Central Archive, including its staff, publications and research. The Archive's 'Empirical Social Research' library can be accessed and searched via internet as well as the Data Catalogue. This site also informs about the Zentrum für historische Sozialforschung [Centre for Historical Social Research] and its research projects.