Barro-Lee Educational Attainment Dataset -- The much-used Barro-Lee data provide data on various measures of educational attainment in 5-year increments for 1950 onwards.
Census Bureau (U.S.) -- The Census Bureau gathers a dizzying amount of social, demographic, and economic information about the United States through various means. The Subject Index is a good starting point for browsing and searching through the Bureau's wealth of information. The Census Bureau's education-themed data cover topics such as educational attainment, school enrollment, and school finances.
College and Beyond II: Outcomes of a Liberal Arts Education (CBII) -- The CBII project is an attempt to assess the merits of liberal arts educations and higher education more broadly by collecting data on students at various public institutions during their time in college and, for a subset of those students, their post-graduation experiences in terms of health, labor markets, civic participation, and inequality. The data from the project are being released via the ICPSR at the University of Michigan. Note that the data are not available for download and are instead available via application only.
College Scorecard Data -- The College Scorecard provides data on colleges and universities with regard to admissions, standardized test scores, student demographics, costs of attendance, completion rates, and post-graduation earnings. Some data from the Scorecard are also available via the ICPSR.
Current Population Survey (CPS) -- The Current Population Survey is a joint project between the Bureau of Labor Statistics and the U.S. Census Bureau. The CPS is a monthly survey that collects basic socio-demographic information, labor force characteristics, and economic status. With regard to education, it also provides detailed data on educational attainment and enrollment. To access CPS data files, users can download data via https://www.census.gov/programs-surveys/cps/data/datasets.html or use various tools for creating tables from the microdata. Alternately, they can go to the National Bureau of Economic Research's CPS site or to IPUMS-CPS.
Education Policy and Data Center (EPDC) -- The Education Policy and Data Center provides access to education measures and indicators from a range of sources such as administrative records, household surveys, and assessment tests. Users can search for data by country, topic, or level of education.
EDStats - the World Bank Education Statistics Database -- EDStats contains an extensive range of international data pertaining to education, both in tables and databases. The EdStats Query may be of particular interest because it allows users to query an extensive database of time-series data and also provides access to various other World Bank collections of data on educational attainment and expenditure. Bulk downloads of EdStats data are available at https://datacatalog.worldbank.org/search/dataset/0038480. EdStats and other World Bank education data are part of the Bank's Data Catalog.
Global Educational Attainment 1970-2015 -- This dataset from the Global Health Data Exchange "provides estimates of average years of educational attainment per capita for people over the age of 15 for the years 1970-2015 by year, sex, and age group for 188 countries." See https://ghdx.healthdata.org/keyword/education for other education-themed data from the GHDx.
Higher Education Research Institute (HERI) -- UCLA's Higher Education Research Institute conducts recurring surveys on college freshmen, college seniors, and faculty. Data from many of their surveys are available for researchers upon application.
National Center for Education Statistics -- The NCES is the primary federal entity for collecting and analyzing data and statistics in the United States and in various other countries. The NCES has many data collection programs and surveys, covering topics such as assessment, elementary and secondary schools, higher education, and international comparisons of education outcomes. There are also multiple tools for accessing NCES data. The Digest of Education Statistics and other NCES publications are also very useful as staring points for tracking down data collected by the NCES and other federal agencies. For other data collected by the Department of Education, see its Data & Statistics collection and its EDFacts Initiative.
National Center for Education Statistics International Data Explorer -- The NCES International Data Explorer, which is part of the NCES' International Activities Program, provides access to data from various international programs that assess students' skills in literacy, mathematics, sciences, and other areas. The NCES provides additional information about international education-assessment programs at http://nces.ed.gov/surveys/international/assessments.asp. Click on a link to a given program to get more information about subject coverage, participating countries, and data access.
National Longitudinal Survey of Freshmen (NLSF) -- The NLSF, which is housed at Princeton University's Office of Population Research, follows a cohort of college freshmen over time, with the intent of testing competing theories/explanations for underperformance of minorities in higher education. The data are available upon registration from the OPR.
National Science Foundation National Center for Science and Engineering Statistics (NCSES) -- The National Science Foundation collects much data on education and the sciences, including topics such as degree completions and educational attainment, skill levels among the labor force, public and private expenditures on research and development, and public attitudes towards the sciences. The NSF provides various tools and interfaces for accessing both aggregated statistics and microdata from NSF surveys. There are also many statistical publications available. Statistics from older NSF data-collection programs are also available via the Industrial Research and Development Information System (IRIS). Microdata from NSF surveys of undergraduates and recipients of doctoral degrees are also available via IPUMS HigherEd. Data from NSF surveys of the public's knowledge of and attitudes towards science are also available via the Roper Center for Public Opinion Research.
PolicyMap -- PolicyMap allows you to map out data on population demographics, income, poverty, housing, crime, health, the environment, education, and other topics. Uses can map out data at various levels of geogprahy - states, counties, ZIP codes, or Congressional districts, depending on the data. You can also download data in spreadsheet-friendly formats. PolicyMap is also available via Databases at Emory.
Social Explorer -- Social Explorer provides quick and easy access to current and historical census data and demographic information. Its contents include the entire U.S. Census from 1790 to 2020, annual updates from the American Community Survey, data on religious congregations for the United States for 2009, decennial religious congregation data for 1980-2010, economic data on businesses, crime data, health indicators, and carbon emissions data for 2002. Users can create reports and maps at various levels of geography, including counties, Census tracts, Census block groups, and ZIP codes, depending on data availability. Social Explorer is also available via Databases at Emory.
UNESCO Institute for Statistics -- The United Nations Education, Scientific, and Cultural Organization (UNESCO) provides, to quote the website, "[global] and internationally comparable statistics on education, science, technology, culture, and communication." Users can download tables directly into Microsoft Excel via UIS.Stat.
U.S. Schools - Desegregation Court Cases and School Demographic Data -- This project at Brown University "includes data for the period 1970-2010 about desegregation court cases, trends in racial composition and segregation of elementary schools, and additional information about poverty, teacher-student ratios, and performance on standardized state tests. For every U.S. school district, information on racial and ethnic composition of the elementary student population for available years, and summary indices of school segregation and disparities are posted." This project is part of the American Communities Project's collection of projects on urbanization, demographics, education, and inequalities.