"Lean in" is the current mantra for women in the business world, thanks to Facebook COO Sheryl Sandberg. She encourages women to be ambitious, to take risks, even when they are scared or worried about how their work will mesh with their family obligations. It's an admirable notion, and if I were just getting out of college, something that I would embrace.

But some industries, like Big Law, don't just need women lawyers who are hungry and smart and willing to bill punishingly long hours alongside their male colleagues. Firms also need to make top-down, institutional changes to achieve greater gender parity and advancement. (Currently, women constitute 15 percent of the equity partnership at the big firms and half of the associates.)