Men start negotiations sooner, expect more frequent negotiations, ask for more in opening offers and then concede less than women. Authors Linda Babcock and Sara Laschever try to explain the difference in a soon to be published book titled ?Women Don?t Ask? from Princeton University Press. The research shows that reluctance to negotiate can have severe economic consequences.
See "Can negotiating skills cause gender pay gap?", Alan Krueger, NYT, International Herald Tribune, August 21, 2003