National statistical offices

Bulgaria - National Statistical Institute
Croatia - Central Bureau of Statistics
Czech Republic - Czech Statistical Office
Estonia - Statistical Office of Estonia
Hungary - Central Statistical Office
Latvia - Central Statistical Bureau of Latvia
Lithuania - Lithuanian Department of Statistics
Moldova - Department of Statistical and Sociological Analysis
Poland - Central Statistical Office
Romania - National Institute of Statistics
Serbia and Montenegro - Federal Statistical Office
Slovakia - Statistical Office of the Slovak Republic
Slovenia - Statistical Office of the Republic of Slovenia
Ukraine - State Committee of Statistics of Ukraine

Other data sources and links

GESIS East European Data Archive Network
Balkan Academic News
UCLA Center of European and Eurasian Studies
Eurostat
WHO Regional Office for Europe
Soyuz: The Research Network for Postsocialist Studies
Central and Eastern European Network on Migration Research
Historical Population Statistics
Contextual Database of the Generations and Gender Program
Social Stratification In Eastern Europe After 1989
Luxembourg Income Study
Center for Population Studies, Bulgaria