The article argues that home equity borrowing is an instance of Max Weber's concept of increasing rationalization of society. The dramatic growth in U.S. home equity borrowing is associated with an increasingly fungible orientation to the home, in which a significant portion of this borrowing is used to fund additional spending on consumer goods. Survey data are used to support the notion that rationalization is spread by a process of diffusion.JEL classification: A13, B52, D11