Someone I worked with had asked for recommendations when I noted the speaking lineup of a conference he was attending was exclusively men, and I figured I'd share the letter I came up with in case it is useful to others:
While I attended $CONFERENCE_NAME last weekend, I was disappointed to notice the oversights in your speaker line up leading to it being made up of nothing but men. Perhaps your prioritization of people with their own books to sell led to inadvertent systematic discrimination, as you were reliant on the discriminatory publishing world and more generally on people without a significant non-work-related demands on their time (who are most likely to be either single men or men in non-egalitarian marriages.) {Depending on your impression of the conference itself, something like: "Since I was also disappointed in how much of the conference devolved into the speakers plugging their own books, I am confident you could kill two birds with one stone by instead seeking out the most qualified speakers.” could fit here too.}
I wanted to convey that when trying to build a group from $COMPANY to attend this weekend, a woman who is normally excited to attend local conferences had no interest at all. Without any women speaking, a code of conduct or even the barest token of effort towards diversity, there was no evidence that there would exist other women there or that the men involved see women as peers. She expected that the weekend would, at best, be full of getting interrupted so men could explaining things she already understood, dudes hitting on her, men quizzing her about the alien experience of being "one of those", people assuming she was part of the conference organizing staff or from recruiting or some attendee’s wife, or simply ignoring her all together. She also assumed that any complaints would be brushed off as disruptive to the existing exclusionary atmosphere that it appears the organizers have cultivated.
Going forward, if I see another line up of all men speaking in Boston, I will have to assume she’s right and you are actively working to run a conference to alienate women. Since I’m not interested in that environment, this may be my last $CONFERENCE_NAME conference; I could instead have attended $OTHER_CONFERENCE_THAT_MADE_AN_EFFORT the week before where both I and the women I know would both have felt more welcome.
Now, the reasoning behind this approach. I like trying to turn it into a contest between conferences, since the only eventual pressure to change will come through economic pressure. It also circumvents the argument that it's not possible or there are no qualified women, without ever having to point out just how incredibly insulting that argument is. Other conferences have worked hard to change the make up on their conventions: accepting speakers through blind proposals (rather than just inviting people they know of or their currently-non-diverse attendees recommend), advertising a code of conduct widely and enforcing it when it comes up, creating scholarships for women who want to attend but who’s companies won’t support it and seeking out and addressing feedback from women speaking and attending. It’s not like this stuff is easy; it’s jut possible.
I did have one more recommendation for the guy I was talking with:
If you want to be helpful while you are there, be your usual polite and outgoing and aware self and discuss the technical work of any women you do meet, especially listening to their ideas and learning about the work they are doing. A good interaction or two can brighten up even the most awkward conference.