Jewish Studies Research Guide: Religion and Religious Practices

Adherents.com

Data on religious group membership.

American Religion Data Archive

Preserves and provides access to data on American religion.

General Social Surveys

Personal opinion surveys of U.S. households conducted regularly since 1972 by the National Opinion Research Center.

Inter-University Consortium for Political and Social Research

Vast archive of social science data for researchers.

Pew Forum on Religion and Public Life

A project of the Pew Research Center, provides survey data, news and publications.