Examination of the participation of women in physics and astronomy at each step up the academic ladder, starting with high school and ending with college and university faculty. Comparison of the representation of women earning bachelor's degrees and PhDs in physics and astronomy with the representation of women in other scientific disciplines. The authors look at how the representation of women earning degrees in various scientific disciplines has changed over time and at the question why women disproportionately leave these fields in stead of moving up the academic ladder.