The National Establishment Time Series (NETS) is a private sector source of U.S. business microdata. Researchers have used state-specific NETS extracts for many years, but relatively little is known about the accuracy and representativeness of the nationwide NETS sample. We explore the properties of NETS as compared to official U.S. data on business activity: The Census Bureau’s County Business Patterns (CBP) and Nonemployer Statistics (NES) and the Bureau of Labor Statistics’ Quarterly Census of Employment and Wages (QCEW). We find that the NETS universe does not cover the entirety of the Census-based employer and nonemployer universes, but given certain restrictions NETS can be made to mimic official employer datasets with reasonable precision. The largest differences between NETS employer data and official sources are among small establishments, where imputation is prevalent in NETS. The most stringent of our proposed sample restrictions still allows scope that covers about three quarters of U.S. private sector employment. We conclude that NETS microdata can be useful and convenient for studying static business activity in high detail.