The Bethesda, Md.-based company said it was the first defense contractor to make the list in 2010.
Companies receiving the award are assessed based on corporate diversity activities.
This year, 587 companies participated in the contest by filling out a questionnaire based on questions regarding CEO commitment, human capital, internal and external communications and supplier diversity.
Northrop recently sponsored a heritage and history education initiative in partnership with the Smithsonian Institution.
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