The idea that men are Better than women at mathematics has been widespread. Many writers on education have taken it for granted; a few have tried to prove it. Unfortunately, the general acceptance of this assumption distorts the test results; achievement rather than innate ability is measured. A comparison of the scores of men and women on various kinds of arithmetic tests is not conclusive, since ability to do arithmetic is partly the result of past and present interest in the subject. Even at an early age, boys are expected to be interested in mathematics. Girls, on the other hand, though they may have equal ability, may be discouraged from learning by the prevailing idea that mathematics is a masculine field.