Traditional ideas about differences between men and women are examined in this introductory learning module in a continuing education program for inservice school media specialists. The librarian's and media specialist's awareness of how false beliefs regarding sex roles are manifested is intended to provide background useful in the evaluation, selection, and acquisition of library materials that will promote sex fairness in their institutions. Based on the premise that unfair, inaccurate assumptions are unconsciously communicated through society's differing treatments of men and women, as well as through the repetition of images which define these treatments, the material addresses four major areas: (1) differences between males and females which are determined by sex, (2) ideas about maleness and femaleness which are inferred from sex-determined differences, (3) why such ideas are unfair to both sexes, and (4) ways in which such ideas are communicated. Six specific assumptions based on innate sex differences are stated, along with illustrations of how each is expressed through the media, how behavior is shaped to support the assumption, and reasons why the assumption is unfair or untrue. Tests and exercises to accompany this module are included in a separate activity book. (FM)