Businesses with one to nine domestic employees (termed here as microbusinesses) spent $6.5 billion on research and development costs in the United States of which $4.5 billion was R&D performed by the microbusinesses themselves. This amount is in addition to the $441 billion spent on domestic R&D performance in 2018 by businesses with 10 or more employees. Data for this InfoBrief comes from the 2019 Annual Business Survey (ABS) (data year 2018), developed and cosponsored by the National Center for Science and Engineering Statistics (NCSES) within the National Science Foundation and by the Census Bureau. The ABS is the primary source of information on R&D expenditures for microbusinesses.