Candidate gender quotas have been an important mechanism in increasing women’s numerical representation in the national legislature, yet little empirical research has examined the adoption of quotas cross-nationally. The adoption of quotas is examined systematically across 71 parties in 11 advanced industrial countries from 1975 to 1995 using Event History Analysis, which allows us to explain the dynamic process of the adoption of quotas. The influences that emerge as the most significant are the presence of women within the highest ranks of the party, the adoption of quotas by another party in the system, and the degree of leftist values held by a party.