Science is an intensely social activity. Professional relationships are essential forscientific success and mentors areindispensable for professional growth. Despitethe scientific ethos of universalism andinclusion, American women scientists frequentlyexperience isolation and exclusion at some timeduring their academic career. By contrast,male scientists enjoy informal but crucialsocial networks. Female scientists developnecessary strategies and defences, but manyleave or achieve less success in science whendeprived of necessary interpersonalconnections. There is indication that changewithin departments is occurring, but this isdependent upon institutional leadership.