In this chapter we discuss the ‘pipeline’ thesis for improving women's participation in science. This ‘supply side’ approach assumes that if sufficient women are encouraged to enter the scientific and engineering professions, the gender gap in science and technology will disappear.

The scientific career track, from elementary school to initial employment, has been depicted as a ‘pipeline’ like those for the transport of fluids and gases such as water, oil or natural gas. The rate of flow into scientific careers is measured by passage through transition points in the pipeline such as graduation and continuation to the next educational level.

Nevertheless, the flow of women into science is through, ‘a pipe with leaks at every joint along its span, a pipe that begins with a high-pressure surge of young women at the source – a roiling Amazon of smart graduate students – and ends at the spigot with a trickle of women prominent enough to be deans or department heads at major universities or to win such honours as membership in the National Academy of Science or even, heaven forfend, the Nobel Prize’ (Angier, 1995). Even this negative depiction of the pipeline as a leaky vessel is too optimistic. As we shall see, many women are discouraged from pursuing their scientific interests far earlier in their educational career than graduate training.

Although the rate of women entering scientific professions has improved significantly, especially in the biological sciences, the numbers reaching high-level positions are much smaller than expected.