Gender segregation is a cornerstone of the techno-political order in much of the Middle East and North Africa. In most Arab countries, for example, the public schooling system in which young citizens are socialized daily for more than a decade is segregated by law. Yet in the Gulf, segregation covers a much broader terrain, cutting across not only schools but also hospitals, restaurants, shops, government offices, buses, and parks, among other public places. While religious conservatives argue that spatial and technical segregation safeguards the moral fabric of society, critics claim the opposite, suggesting that it blocks the formation of a healthy public sphere. Yet gender segregation as social engineering has received only limited scholarly attention. This paper seeks to inject some rare empirical data into the debate, combining experiments in Saudi Arabia and Kuwait with qualitative fieldwork evidence. Consistent with critics’ arguments, findings suggest a set of moral and civic costs linked to the gender-segregated status quo, with the implication that desegregation—or greater “gender mixing” in the local parlance—would indeed lead to moral and civic dividends, such as greater open-mindedness, tolerance, ethics, and law-abidingness. Findings challenge both the expectations of religious conservatives in the region as well as social dominance theory more broadly, and contribute to our knowledge of state-led social engineering and its implications.