The "2016 Knowledge for Teaching Early Elementary Mathematics" (2016 K-TEEM) test measures teachers' mathematical knowledge for teaching early elementary mathematics. The 2016 K-TEEM is the third version of the K-TEEM (Schoen, Bray, Wolfe, Tazaz, & Nielsen, 2017). In this report, we present results of the first large-scale field test of the 2016 K-TEEM test with 383 practicing educators. The report contains information about the development process used for the test, a description of the sample, descriptions of the procedures used for data entry, scoring of responses, and analysis of data, recommended scoring procedures, and findings regarding the distribution of test scores, standard error of measurement, reliability estimates, and suggestion for additional validation efforts to be conducted in the future.