Diversity in the workplace has been proven to foster innovation and creativity and improve recruitment and retention, and diverse teams are better at solving problems than teams that aren't diverse. Despite all of this, a lot of companies aren't diversifying the way evidence would suggest that they should. Women in the Workplace, a joint study from LeanIn.org and McKinsey, found that women are underrepresented in senior leadership, and a 2014 analysis from Russell Reynolds found that more than 84 percent of board seats in the Fortune 250 are held by people who identify as white. Why aren't companies more diverse, given all we know about diversity's benefits?