Default rules, which apply only if parties opt not to bypass them, are a common and consequential phenomenon in law. These rules fill gaps, serve as the backdrop against which parties make alternative arrangements, and formalize majoritarian social preferences. Through these roles, default rules affect the behavior and outcomes not only of those parties subjected directly to them, but also those who opt out of their reach. Because of this, the construction of default rules is an important policymaking tool. A significant body of theoretical scholarship debates the relative merits of several default rule designs. Among these are majoritarian defaults, which are intended to replicate what the affected parties would have chosen had they expressed their preferences. Such rules are favored in situations where there is little to be gained by forcing individuals to avoid an unpopular default and where there are instead substantial benefits to giving most people what they want. Intestacy— when individuals die without a will or other transfer arrangement for their property—is one such situation. In that situation, the laws of intestacy govern the distribution of property. These laws are intended to approximate the disposition that most individuals would prefer. Yet what if no rule captures what most people want? What if the preferences of those more likely to be subjected to the rules differ from the rest of the population? What if people’s preferences regarding the allocation of their property are socially patterned? This Article takes up these questions, drawing on novel data from a national survey of estate-planning behavior and dispositive preferences (N = 1,975). The results not only document heterogeneity in dispositive preferences but also establish links between these preferences and individual characteristics. These empirical findings challenge assumptions about the existence of a clear majoritarian preference and bring to the fore the possibility that facially neutral default rules may have disparate impacts on some groups. In response, this Article considers the desirability and feasibility of several possible responses, including clarifying the subpopulation whose preferences are prioritized, enhancing the accuracy of default rules with additional empirical evidence, and increasing the complexity of default rules to offer greater personalization. In doing so, this Article not only contributes to current efforts to reform the laws of intestacy but also extends scholarship on default rule design by drawing attention to the challenges of what I term choice building: constructing the content of default rules from the ground up on the basis of empirical evidence.