This article discusses the socially constructed masculinity of unmarried girls among the Borana in southern Ethiopia. The Borana practice the longstanding Gadaa political system, which was inscribed by UNESCO as an intangible cultural heritage of humanity in 2016. Data for this article was gathered through qualitative approaches, including interviews, focus group discussions (FGDs), and direct observation of the 2012 Gadaa general assembly. Such an assembly is held once every eight years to enact new Gadaa rules and amend the existing ones. The findings indicated that the Gadaa system provides rules regulating Borana marriage lives, including premarital virginity for girls. The Borana refers to an unmarried girl as “dubra gammee,” which means “a virgin girl,” who has a masculine identity and is “a male person.” Unmarried girls have certain physical markers, particularly a hairstyle that they share with boys. Any sexual act with unmarried girls is therefore homosexual and punishable. Gadaa and all related institutions care for the premarital virginity of girls. The Gadaa rules impose punishment unconditionally on men who have sex with unmarried girls. On the other hand, the Borana tolerate extramarital sexual relations, which has partly contributed to maintaining the premarital sexual innocence of Borana girls.