This paper argues that a new institution of motherhood was constructed through modernizing reforms in the realms of law and medicine in semi-colonial Egypt. I show that Egyptian women were cast as ignorant of basic principles of health and hygiene and blamed for the high infant mortality rate in turn-of-the-century Egypt. This coincided with an ongoing reorientation of the Egyptian family in popular and religious literature, wherein the woman was being recast as the central figure in shaping the child and tending the home. At the intersection of these phenomena, new discussions emerged about the significance of women as mothers and the proper way to perform motherhood as an Egyptian woman. A new institution of motherhood was then constructed, concretized, and enforced through medical and legal discourse and interventions that were opposable against women across Egypt. I show that British and Egyptian lawmakers privileged the role of women as mothers in debates surrounding the drafting of new labor legislation and that they sought to ensure the maturity of mothers and the mental and physical health of the Egyptian family in a series of controversial personal status law reforms throughout the semi-colonial period. Through a socio-legal history of the institution of motherhood, my paper examines how colonialism, nationalism, and claims to modernity affected Egyptians' daily lives and accessed family homes and women's bodies. Throughout the paper, I emphasize a conceptualization of modernization as a dialectical process. Modernization claims to liberate individuals, women, or a nation, but, at the same time, it creates elaborate structures for their discipline. My paper treats the institution of motherhood as one such structure and explores the roles of hygiene and domestic cleanliness, coloniality, and law in its construction in semi-colonial Egypt.