The Australian Scholastic Test (ASAT) was first used as a moderating device in the Australian Capitol Territory in 1977. Differences have been observed in the average performance of males and females on the test. The study reported in this monograph investigated the nature and origin of the score differences recorded for ASAT The research focused on five issues: retention rate differences, attitude differences, preparation differences, item bias, and effect of differential course selection. The findings indicated that sex had no significant direct effect on ASAT scores. The observed differences in male and female ASAT scores were related to English ability, experience in mathematics, and confidence in success. The different patterns for staying longer at school could explain much of the observed variations between males and females. (Author)