The Data Archive for the Social Sciences is a department within GESIS Leibniz Institute for the Social Sciences. Its primary focus is providing excellent data service for national and international comparative surveys from the fields of social and political science research. These surveys, which must comply with clearly defined methodological and technical requirements, are archived and processed according to internationally recognized standards and made accessible to the scientifically interested public in a user-friendly manner. Reference studies such as ALLBUS and other surveys for which there is a large demand are combined into 'study collections' accompanied by special services – frequently in cooperation with the primary researchers or experts. For example, variables are harmonized and standardized in order to facilitate comparisons across time or regional units. Three Research Data Centers have been established in cooperation with the department „Social Monitoring and Social Change“: for the ALLBUS, for selected international survey programmes and for the extensive series of studies in electoral research. User advice is provided on finding relevant data and on data analysis, and researchers are introduced to complex techniques of data analysis in our training seminars.