We quite simply can't afford to miss out on the contributions of half the population. The numbers of women in tech are plummeting: Women were 35% of CS majors in 1985, but only 18% today. Women are missing out on high-impact, flexible, well-paid, and exciting careers, and the industry is missing out on their ideas. By 2020 the United States will have 1 million unfilled roles in computer science and engineering — if women majored in CS at the same rate as men we could cut this gap in half.