This article examines the constitutional challenges that lawmakers in the United States may face when devising legislation intended to increase the diversity of corporate boards of directors, based on factors such as gender and race. Specifically, the study evaluates two California statutes that imposed quota systems on private corporations in order to increase board membership by women and others from under-represented communities. The article then analyses the courts’ rationale for deeming the legislative measures unconstitutional and concludes by proposing that extra-governmental methods, such as shareholder activism or stock exchange-imposed diversity requirements, may prove more durable in advancing board diversity interests than legislation.