Social role theory originated as an effort to understand the causes of sex differences and similarities in social behavior. In the 1 980s when the theory emerged, many research psychologists had begun to use meta-analytic methods to aggregate research findings bearing on the issue of whether female and male behavior differs (Eagly, 1 987). These researchers had to come to terms with the persisting presence of differences in these data. Although these differences were typically not large (Eagly, 1 995 , 1 997a; Hyde, 1 996), they were often large enough to be consequential, particularly in view of the substantial cumulative impact that small differences can have if repeatedly enacted over a period of time (Abelson, 1 985 ; Martel l , Lane, & Emrich, 1 995). The more accurate description of sex differences and similarities produced by quantitative reviewing, compared with earlier narrative reviewing (e.g., Maccoby & Jacklin, 1 974), allowed more systematic examination of important issues such as the variation of differences and similarities across situations . More val id descriptions

brought a flowering of theory, as some researchers were inspired to renew their efforts to develop theories that explain the intriguing patterns of difference and similarity present in psychological findings (e .g . , Ashmore & Del Boca, 1 986; Beall & Sternberg, 1 993 ; Deaux & Major, 1 987).