Both in the United States and in Europe, board diversity efforts are frequently justified by the “business case” that diversity makes companies more profitable. But that case is weak. In fact, a number of academic studies have concluded that gender diversity on boards negatively impacts firm performance. But as such studies face several methodological hurdles, it's safe to say that although the business case for board diversity has not been proven, neither has the case against it. This is not a reason to be skeptical of board diversity. In this day and age, there is no reason that corporate boards should remain the exclusive province of white males. But we must be realistic about what board diversity — and quotas, in particular — will accomplish.

Kimberly D. Krawiec, What Does Corporate Boardroom Diversity Accomplish?, The New York Times (April 1, 2015).