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 re- lation to corporate innovation. Boards are more likely to include women in countries with narrower gender gaps, higher female labor market participation, and less masculine cul- tures. 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 in- novative corporate cultures, and more diverse inventors, characteristics that are conducive to an improved innovative performance.