A couple of years ago I attended an American Physical Society conference on underrepresented minorities in physics, including women. The low numbers of women who choose physics is a concern for the society and there are many causes including, I believe, the way physics is taught. The culture is one where students are always being challenged, sometimes rather rudely. This is not a culture which is comfortable for those who are not supremely confident of their own abilities and since most physicists are trained in the same way, this can permeate all the way down to physics instruction in high school. I think that more and more physics department in universities are trying to change this culture and it sounds like Harvey Mudd, which is not an LAC but rather part of the [Association of Independent Technical Universities (AITU)](http://theaitu.org) is doing an outstanding job.
At my university, Illinois Tech (also an AITU school), we typically have 25-30% women in our undergraduate program and graduate programs. These are not great numbers but much better than when I started at the university 33 years ago and pretty much match the number of women we find in engineering. In the graduate program, it is absolutely clear that one way of keeping women (and not just women) in the program all the way through is to make sure that periodic evaluations of the student’s progress are not simply based on written exams but a full assessment of the student’s potential to do research. This is clearly a big change that has been made and a number of other programs are trying to do this too. Another change that we have tried to make in our undergraduate program is to emphasize that one can be a physicist without having to obtain a PhD; that physicists at all levels find jobs in many different fields and bring their training and thought processes with them. This kind of attitude encourages students to see the physics degree as valuable in itself not just as a stepping stone to a PhD.
I think that as we have more physics students trained in this way teaching in high schools, it might be possible to have more women and other minorities see it as a viable major and be encouraged to take advanced physics courses.