Essay scores generated by machine and by human raters are generally comparable; that is, they can produce scores with similar means and standard deviations, and machine scores generally correlate as highly with human scores as scores from one human correlate with scores from another human. Although human and machine essay scores are highly related on average, this does not eliminate the possibility that machine and human scores may differ significantly for certain gender, ethnic, or country groups. Such differences were explored with essay data from two large-scale high-stakes testing programs: the Test of English as a Foreign Language and the Graduate Record Examination. Human and machine scores were very similar across most subgroups, but there were some notable exceptions. Policies were developed so that any differences between humans and machines would have a minimal impact on final reported scores. (Contains 7 tables and 1 footnote.)