As Aristotle recognized in The Politics, the household is an indispensable building block of social, economic, and political life. A liberal society grants its citizens far wider berth to arrange their households than to choose their familial and marital relationships. Legal commentators, however, have devoted far more attention to the family and to marriage than to the household as such. To unpack the household, this Article applies transaction cost economics and sociological theory to interactions among household participants. It explores questions such as the structure of ownership of dwelling units, the scope of household production, and the governance of activities around the hearth. Drawing on a wide variety of historical and statistical sources, the Article contrasts conventional family-based households with arrangements in, among others, medieval English castles, Benedictine monasteries, and Israeli kibbutzim. A household is likely to involve several participants and as many as three distinct relationships—that among occupants, that among owners, and that between these two groups (the landlord-tenant relationship). Individuals, when structuring these home relationships, typically pursue a strategy of consorting with intimates. This facilitates informal coordination and greatly reduces the transaction costs of domestic interactions. Utopian critics, however, have sought to enlarge the scale of households, and some legal advocates have urged household members to write formal contracts and take disputes into court. These commentators fail to appreciate the great advantages, in the home setting, of informally associating with a few trustworthy intimates. author. Walter E. Meyer Professor of Property and Urban Law, Yale Law School. I am grateful for comments from participants in the Cornell University Social Science Seminar; the Harvard-MIT Organizational Economics Seminar; a conference on Norms and the Law hosted by the Center for Interdisciplinary Studies, Washington University School of Law; and law and economics workshops at Harvard Law School, University of Southern California Law School, and Yale Law School. I thank, for their suggestions, Anne Alstott, Scott Altman, Jennifer Arlen, Stephen Bainbridge, Yochai Benkler, Hanoch Dagan, Eric Fleisig-Greene, Robert Gibbons, Oliver Hart, Jill Hasday, Joni Hersch, John Langbein, Amnon Lehavi, Avital Margalit, Daniel Markovits, Steven Nock, Eric Rasmusen, Roberta Romano, Martha Roth, Scott Shapiro, Reva Siegel, Brian Simpson, Katherine Stone, Lynn Stout, Jay Weiser, James Whitman, and especially Margaret Brinig, Henry Hansmann, Richard McAdams, Robert Pollak, and Henry Smith. William Baude, YiLing Chen-Josephson, and John Eisenberg provided able research assistance. ELLICKSON – PRE-OP 11/6/2006 5:37:59 PM unpacking the household 227 article contents