  This paper examines the historical dimension of gender bias in the US
computing workforce. It offers new quantitative data on the computing workforce
prior to the availability of US Census data in the 1970s. Computer user groups
(including SHARE, Inc., and the Mark IV software user group) are taken as a
cross-section of the computing workforce. A novel method of gender analysis is
developed to estimate women's and men's participation in computing beginning in
the 1950s. The data presented here are consistent with well-known NSF
statistics that show computer science undergraduate programs enrolling
increasing numbers of women students during 1965-1985. These findings challenge
the 'making programming masculine' thesis, and serve to correct the
unrealistically high figures often cited for women's participation in early
computer programming. Gender bias in computing today is traced not to 1960s
professionalization but to cultural changes in the 1980s and beyond.
