Keywords: Challenges of comparative research and International Survey Projects, cross-cultural concerns in data collection and measurement issues

In the dawn of 21st century, the democracies began granting legal rights to same-sex marriage. A few studies examined the economic, political, and cultural conditions on same-sex marriage legalization, and less attention has been paid to how the institutional change affects people’s gender values. We explore the effect, reducing the traditional gender ideology and extending their gender difference, of institutional change on people. Using the 2012 International Social Survey Programme (ISSP) data from 34 industrialized countries, this paper demonstrate that the average traditional gender ideology difference would be less in same-sex marriage and civil unions counties then in restrictive counties, and the ideology gap between male and female increase with the opening of the marriage law in their countries. We find that, after the institutional change, there is a stronger effect of lifetime learning on reducing the traditional gender ideology, and extending gender gap of the ideology, which implies that women change their gender ideology much faster than men from the traditional ideology of patriarchy. Moreover, both in legalized and restricted countries, individual’s traditional gender ideology would reduce as their age increases. By applying the Multi-level model explanation to a comparative context of industrialized countries, we illustrate the effect of institutional change and socialization process of individual change on gender values along their life time.