Employees advance less well when the managers evaluating them do not share the same race or gender. The managers tend to disagree more (though only slightly) in how they evaluate the employee’s performance. These small differences in evaluation have significant consequences for the promotion and pay gaps in the firm over time.

Castilla, Emilio J. 2011. “Bringing Managers Back In: Managerial Influences on Workplace Inequality.” American Sociological Review 76(5): 667-94.