The primary questions investigated are: Is it true that males excel in mathematical problem solving and, if so, when does this superiority develop? An examination of recent research showed that sex-related differences did exist, although small, even after controlling for mathematics background. Differences appeared in early adolescence and were found only with subjects of above-average ability and on problems whose content is spatial or sex-biased. Eliminating sex bias in tests eliminates or reduces differences. The remaining differences are probably involved with social attitudes toward problem solving as a male activity. (MP)