The superiority of males in mathematics achievement from grades eight through college is evident, and the following causes of sex differences in mathematics achievement are considered in the paper: spatial ability, enrollment in mathematics courses, social factors, anxiety, attitudes, and developmental differences between the sexes. Alleviating the differences is presented by addressing the need for females to study more mathematics, to improve in spatial visualization, to decrease math anxiety, and to overcome social factors which singularly and in combination hinder the mathematical achievement and advancement of females throughout their lives. Educators, parents and students must recognize the problem, understand the nature and causes of the problem, and then attack the problem from a multi-faceted perspective addressing both the needs of the students and the causes that have produced the existing differences in achievement. (Author)