Consider the following statistics.

Girls receive higher grades than do boys, from kindergarten through college, including grades in mathematics. In the latest year for which we have data, girls comprised 48% of all college math majors, took 56% of all Advanced Placement exams, and took 51% of AP calculus exams [College Board 2008]. Yet, only 17% of AP computer science test-takers in that year were female [College Board 2008].

Likewise, although 57% of all 2008 undergraduate degree recipients were female, women comprised only 18% of computer science (CS) and information (IT) degree recipients [National Center for Education Statistics 2008].

Curiously, 23 years earlier (in 1985), 37% of computer science bachelor’s degrees were awarded to women [National Center for Education Statistics 2008]. Between 2001 and 2008 alone, there was a 79% decline in the number of incoming undergraduate women interested in majoring in computer science [Higher Education Research Institute 2008].

Why are so few women in computer science? Should we care? And, if we should, can anything be done to reverse these trends? Debates over these issues fall into three major categories.

Some argue that women are less likely than men to possess cognitive abilities at the extreme right tail of the distribution, which are necessary to compete in computer science (see [Ceci and Williams 2007], [Ceci and Williams 2010], and [Halpernet al. 2007]).

Others say that women are not as interested in computer science and simply prefer to study other subjects [Ferriman et al. 2009]; [Durndell and Lightbody 1993]; [Seymour and Hewitt 1994], and still others argue that women are directed out of the field by stereotypes, biases, and “male culture” [American Association of University Women 2000]; [Margolis et al. 2000].

This chapter reviews the research pertaining to each of these three positions and follows each argument through to its logical implications.