Links

IMAG (The International Microdata Access Group)
The International Microdata Access Group (IMAG) was formed to foster the international collaboration of researchers who work with historical and contemporary microdata in order to facilitate transnational comparative research.
The mission of IMAG is to preserve original population data, microdata, and their supporting documentation, and to improve access to these data in accordance with national confidentiality standards.

IPUMS (Integrated Public Use Microdata Series)
census microdata for social and economic research
IPUMS-USA is a coherent national census database spanning 1850 to 1990.
IPUMS-International is a new project dedicated to collecting and distributing census data from around the world. Its goals are to: 

Collect and preserve data and documentation

Harmonize data

Disseminate the data absolutely free!