There has been much public outcry over the data-tracking practices of governments and corporations and how these threaten civil liberties. Meanwhile, people have increasingly embraced wearable technologies and smartphone apps to monitor and analyze their own bodies and lives. How do individuals "datafy" themselves and how, in turn, does data intimately shape their experience, identity, and life chances? What does contemporary self-tracking (and its pre-digital antecedents) reveal about changing cultural values, political contexts, and understandings of the self?