data.gov (repository of US federal, state, local, and tribal data)
Harvard's Henry A. Murray Research Archive (qualitative data)
University of California, Irvine (UCI) Network Data Repository
University of California, Berkeley SDA: Survey Documentation and Analysis (online data analysis tool for multiple datasets)
Pew Research Center (free account required to download datasets)
Censuses:
U.S. Census | data.census.gov (main data page) | American Community Survey (ACS) (largest U.S. Census survey, with ongoing monthly data on ancestry, educational attainment, income, migration, disability, employment, and housing)
Integrated Public Use Microdata Series (IPUMS) | IPUMS USA (numerous datasets based on census individual records for the U.S. and other nations)
General/Omnibus (Cross-sectional):
General Social Survey (US) | FAQ | weights
Eurobarometer (European nations)
International Social Survey Programme (international, with modules on specific issues)
Survey Center on American Life (a project of the American Enterprise Institute)
World Values Survey (all regions of world)
General/Omnibus (Longitudinal):
American Trends Panel (ATP): Pew Research Center probability-based survey panel made up of roughly 10,000 adults who are selected at random from across the entire United States; while technically a panel survey, this survey adds new respondents in every wave and is mainly used to provide a snapshot of U.S. public opinion at any given moment
Longitudinal Study of Generations: longitudinal study of four generations of California families begun in 1971
National Longitudinal Surveys: Bureau of Labor Statistics surveys dealing with major life events and labor-market activities; includes National Longitudinal Studies of Youth
Panel Study of Income Dynamics (PSID): follows same American families and their descendants since 1968; various supplemental modules
Wisconsin Longitudinal Study (WLS): survey of men and women who graduated from Wisconsin high schools in 1957
Crime (U.S.):
The Violence Project (mass public shootings in the United States since 1966)
Economic (U.S.):
Annual Social and Economic Supplement (ASEC) (annual survey focused on income and poverty conducted by the US Census)
Bureau of Labor Statistics (US data on employment, labor unions, etc.)
Current Population Survey [data files] (monthly survey of households focused on employment and conducted by the US Census for the BLS) | Labor Force Statistics (BLS-curated statistics by age, education, gender, marital status, race, etc.)
Survey of Consumer Finances (U.S. Federal Reserve survey of family savings, income, pensions, etc.)
Survey of Income and Program Participation (U.S. Census panel survey on household income and participation in income-transfer programs)
U.S. Department of Agriculture (USDA) Atlas of Rural and Small-Town America (county-level data on jobs, income, etc.)
Economic (Global):
Global Repository of Income Dynamics (GRID): open-access dataset with administrative panel data (e.g., Social Security and tax records) harmonized across 13 countries (including the U.S., Argentina, Brazil, Canada, Mexico, and European countries) on income inequality, income volatility, economic mobility, and other income dynamics
LIS Cross-National Data Center | Luxembourg Income Study (harmonized microdata from about 50 countries in Europe, North America, Latin America, Africa, Asia, and Australasia spanning five decades) | Luxembourg Wealth Study (first cross-national wealth database in existence)
Education:
American Freshman Survey (first-year students at colleges and universities)
Early Childhood Longitudinal Program (ECLS) (longitudinal studies examining child development, school readiness, and early school experiences of children followed from kindergarten or earlier)
High School & Beyond (longitudinal study following 10th and 12th graders in 1980)
Program for International Student Assessment (international survey of student performance in math, science, and reading)
Virginia Longitudinal Data System (education and workforce development)
Environment:
Families:
Changing Lives of Older Couples (spousal bereavement)
Fragile Families and Child Wellbeing Study (longitudinal, focus on unmarried parents and children)
Longitudinal Study of Generations (longitudinal study of four generations of California families begun in 1971)
National Survey of Family Growth (NSFG) (family life, marriage/divorce, pregnancy, infertility, use of contraception, and men’s and women’s health)
Wisconsin Study of Families and Work (longitudinal study of work-family balance and children’s socio-emotional development)
Health (U.S., Cross-sectional):
Behavioral Risk Factor Surveillance System (BRFSS) (CDC state-based survey on health-related risk behaviors, chronic health conditions, and use of preventive services)
Health and Retirement Study (data on aging in America since 1990)
Medical Expenditure Panel Survey Household Component (MEPS HC)
National Health Interview Survey (NHIS) (tracking health status and health care access since 1957)
Youth Risk Behavior Surveillance System (YRBSS) (CDC survey of health-risk behaviors among youth and young adults)
Health (U.S., Longitudinal):
Midlife in the United States (MIDUS) (national longitudinal study of health and well-being)
Monitoring the Future (MFT) (ongoing study of the behaviors, attitudes, and values of Americans from adolescence through adulthood, which covers topics like substance use and includes both an annual survey of 8th, 10th and 12th grade students and follow-up surveys every two to five years of an adult subsample of each graduating class)
National Longitudinal Study of Adolescent to Adult Health (Add Health)
National Social Life, Health, and Aging Project (NSHAP) (longitudinal study of health and social well-being of older Americans)
Health (Global):
Demographic and Health Surveys Program (USAID-sponsored program with global data on fertility, family planning, maternal and child health, gender, HIV/AIDS, malaria, and nutrition)
Gateway to Global Aging Data (population survey data on aging around the world)
Internet and Social Media:
Pew Internet & Tech Datasets (Core Trends Survey has Social Media use data)
Media/Publications:
Organizations:
History of Capitalism (corporations)
Oral Histories:
Shoah Foundation (Holocaust survivors)
VCU Libraries:
Sociology Research Guide | Data Sources | Data & Statistics Research Guide | Databases (full listing of data repositories)