Maria Klawe has written an interesting and insightful article on the issue in The Conversation recently. Here’s the essence…

I’ve been working on this issue for decades. When I came to Harvey Mudd College in 2006, the CS department was averaging only about 10% women majors. The faculty had decided to make significant changes to attract more women.

They redesigned their introductory computer science courses to focus less on straight programming and more on creative problem-solving. They included topics to show the breadth of the field and the ways in which it could benefit society.

In order to reduce the intimidation factor for women and other students with no prior coding experience, they split the course into two sections, black and gold (Harvey Mudd’s colors), with black for those who had prior programming experience and gold for those with no prior experience.

This worked wonders to create a supportive atmosphere. […]
Within four years, we went from averaging around 10% women majors to averaging 40%. We have continued to average 40% since 2011.

via Closing the computer science gender gap: how one woman is making a difference in many lives.