Most people seem to agree that individuals have too little privacy, and most proposals to address that problem focus on ways to give those users more information about, and more control over, how information about them is used. Yet in nearly all cases, information subjects are not the parties who make decisions about how information is collected, used, and disseminated; instead, outsiders make unilateral decisions to collect, use, and disseminate information about others. These potential privacy invaders, acting without input from information subjects, are the parties to whom proposals to protect privacy must be directed. This Article develops a theory of unilateral invasions of privacy rooted in the incentives of potential outside invaders...