Using a novel database of firm patents and board characteristics across 45 countries, we examine both within- and cross-country determinants of board gender diversity and its relation to corporate innovation. Boards are more likely to include women in countries with narrower gender gaps, higher female labor market participation, and less masculine cultures. Firms with gender diverse boards have more patents and novel patents, and a higher innovative efficiency. Further analyses suggest that gender diverse boards are associated with more failure-tolerant and long-term chief executive officer (CEO) incentives, more innovative corporate cultures, and more diverse inventors, characteristics that are conducive to an improved innovative performance.