To remain competitive in today’s global economy, businesses and societies rely on contributions from the science, technology, engineering, and mathematics (STEM) workforce. This report provides an overview of the STEM labor force and details its size, growth, educational pathways, salary, and diversity. As in the previous Science and Engineering Indicators report “The STEM Labor Force of Today: Scientists, Engineers, and Skilled Technical Workers,” this thematic report uses an expanded definition of STEM, which includes science and engineering (S&E) occupations, S&E-related occupations, and STEM middle-skill occupations, with the latter defined as occupations that require a high level of knowledge in a technical domain and do not require a bachelor’s degree for entry.^{​See the Technical Appendix in Indicators 2020 report “Science and Engineering Labor Force” for how these occupations were determined.} There is not a standardized way to define the STEM workforce, and other agencies may identify different occupations for their products on the STEM workforce depending on their analytical goals. Readers should use caution when comparing STEM estimates from this thematic report with those from other sources. This thematic report frequently separates people associated with STEM occupations into those with a bachelor’s degree or higher and those without one of those degrees. As with previous labor reports, this thematic report focuses on the non-institutionalized population ages 16–75 years but limits analysis to the civilian population due to limited data on the occupations of active-duty military personnel in some of the data sets used.^{​For the 2021 American Community Survey (ACS), the employed civilian population represents 62.3% of the non-institutionalized population ages 16–75 years, and the civilian population represents 77.1%. For the 2019 ACS, the employed civilian population represents 64.4% of the non-institutionalized population ages 16–75 years, and the civilian population represents 76.6%. For the 2021 National Survey of College Graduates (NSCG), the employed civilian population is 75.1% of the total NSCG population, and the civilian population is 98.7%.} Those enrolled in primary or secondary school are not included. This thematic report’s focus is on occupations that people hold or have held. The majority of this report is about the employed population. In the few sections that discuss those who are not employed, only those records with an associated occupation are included.^{​Records that have occupation information in the ACS include those that are currently employed with a reported occupation or those that were employed within the past 5 years. Occupation data are not recorded for those who have never worked or who have not worked in the past 5 years.} The data used for this thematic report were primarily from the American Community Survey (ACS),^{​Technical documentation for the ACS, including methodology, sample design, and weighting, can be found at https://www.census.gov/programs-surveys/acs/microdata/documentation.html.} the National Survey of College Graduates (NSCG),^{​Technical documentation for the NSCG, including methodology, sample design, and weighting, can be found at https://ncses.nsf.gov/surveys/national-survey-college-graduates/2021#sd.} and the Survey of Doctorate Recipients (SDR).^{​Technical documentation for the SDR, including methodology, sample design, and weighting, can be found at https://ncses.nsf.gov/surveys/doctorate-recipients/2021#sd.}

In the 2021 ACS, among the civilian non-institutionalized population ages 16–75 years, 77.1% of the population were retained for analysis in the employment rates section of the report. About 10,778,018 people were currently enrolled in primary or secondary school (4.4%), and another 42,853,443 were missing occupation data (18.3% of total), had no work experience or had not worked in the last 5 years (0.4%), or previously held military occupations (0.3%).