The purpose of this study was to answer the following questions: (1) In what areas are sex differences supported by research? (2) To what extent are these sex differences caused by biological differences, by differences in socialization, or by differing opportunities? (3) In what way are educators reinforcing sex role stereotypes? In order to determine the influence of educators in the sex role socialization process, the social science literature on the topic was reviewed, and original research was done on the content of textbooks in Ontario. The other two questions were answered through reviews of recent literature. This study concludes that while some sex differences were found in cognitive functioning, aptitudes, and preferences, many of these were not statistically supported until ages 10, 11, and some not until early adolescence. This suggests that schools may be influencing this development. The evidence of stereotyping done by teachers is slight and contradictory; however, evidence does exist for stereotyped content in books and other educational media. In sum, there are many widely held beliefs about sex differences which are not consistently supported by evidence. Annotated bibliographies are included. (Author/JK)