Why are ordinary Moroccans much more likely than Algerians to express supportive attitudes toward gender equality and gender quotas in political institutions? Why do ordinary people throughout the Muslim world vary in their support for women as political leaders? This paper assesses levels of public support for gender quotas among Moroccan and Algerian constituents using data collected by the author in nationally-representative surveys conducted in 2006 and 2007 and over 50,000 public opinion surveys collected in 28 Muslim-majority nations by the World Values Survey since 1981. Morocco and Algeria are highly comparable cases in terms of both culture and religion, as well as aspects of their contemporary parliamentary and electoral institutions. Yet gender quotas were raised to the level of national political discourse by women’s groups in Morocco, resulting in the implementation of an agreement reserving 30 seats for women in 2002 and requiring voters to select two party lists, one for their local constituency and one for the national constituency represented by women. In Algeria, no quota was in place at the time of the study and some prominent female politicians opposed quotas. The data reveal that fully 86 percent of Moroccan constituents reported that they were in favor of gender quotas, compared to 49 percent of Algerian citizens. Moroccans are also much more likely than Algerians to report that they believe women are equally or more able than men to represent their interests in parliament (83 and 55 percent of Moroccans and Algerians, respectively). Employing process tracing in two case studies, Morocco and Algeria, and multivariate analysis of data from over 50,000 public opinion surveys from 28 Muslim-majority nations, this paper tests the effect of gender quotas on political attitudes toward women in parliament. It hypothesizes that implementation of a gender quota explains higher levels of popular support for women in political life because debate about and implementation of quota brings about a process of norm change and learning in society more generally. These findings suggest that, even in authoritarian settings where other effects of quotas, such as the impact of parliamentarians on gender-related legislation or democracy promotion, may be limited, gender quotas positively affect popular beliefs about women as political leaders and are, therefore, highly worthwhile.