Exploratory studies employing volunteer subjects are especially vulnerable to race and class bias. This article illustrates how inattention to race and class as critical dimensions in women's lives can produce biased research samples and lead to false conclusions. It analyzes the race and class background of 200 women who volunteered to participate in an in-depth study of Black and White professional, managerial, and administrative women. Despite a multiplicity of methods used to solicit subjects, White women raised in middle-class families who (...) worked in male-dominated occupations were the most likely to volunteer, and White women were more than twice as likely to respond to media solicitations or letters. To recruit most Black subjects and address their concerns about participation required more labor-intensive strategies involving personal contact. The article discusses reasons for differential volunteering and ways to integrate race and class into qualitative research on women. (shrink)