Lombroso described female criminality as an inherent tendency, a biological atavism. Thomas, and, to a certain degree, Freud extended the physiological explanations of criminality to psychological theories. However, their notions still were based on assumptions of universal physiological traits of women such as their reproductive instinct and passivity. For these theorists and for others such as Thomas, Davis, and Pollak, women are viewed as turning to crime as a perversion of or rebellion against their natural feminine roles. Even today, physiological explanations about female criminality still rely on assumptions about female sex roles. Cowie and Slater identified physical traits of delinquent girls such as bigness with aggressiveness, and other theories have proposed a relationship between female violence and the menstrual cycle. The specific characteristics ascribed to women and critical to theories of female criminality also are uniformly sexual in their nature. In setting hegemonic standards of conduct for all women, the theorists have defined femininity, which they equate with healthy femaleness, in classist, racist, and sexist terms. In their explanations, these writers have created two distinct classes of women: good women who are 'normal' noncriminals, and bad women who are criminals. While differing in their focus and recommended remedies, their major thrust is toward individual adjustment. Most have been concerned with social harmony and the welfare of existing social structure rather than with the women involved or women's position in general. 8 notes and 14 references.