Athey, SusanAvery, ChristopherZemsky, Peter2019-09-292000Athey, Susan, Christopher Avery, and Peter Zemsky. 2000. “Mentoring and Diversity.” American Economic Review 90 (4): 765–86. https://doi.org/10.1257/aer.90.4.765.0002-82821944-7981http://nrs.harvard.edu/urn-3:HUL.InstRepos:41426685We study how diversity evolves at a firm with entry-level and upper-level employees who vary in ability and "type" (gender or ethnicity). The ability of entry-level employees is increased by mentoring. An employee receives more mentoring when more upper-level employees have the same type. Optimal promotions are biased by type, and this bias may favor either the minority or the majority. We characterize possible steady states, including a "glass ceiling, " where the upper level remains less diverse than the entry level. A firm may have multiple steady states, whereby temporary affirmative-action policies have a long-run impact. (JEL J71, J41, D20).en-USJournal Article2019-09-2910.1257/aer.90.4.765