Medicine has been personal since long before personalized medicine became popular as a concept. Health professionals have long taken into consideration individual characteristics of their patients when diagnosing, treating, and caring for them. Why has the notion of personalized medicine become so popular in the new millennium? One reason is the availability of individual-level digital data. Medicine informed by digital, quantified, and computable information about individual patients is now seen as more precise and effective than previous practice based on unstructured data, narratives, and embodied experience. Such an understanding of personalization, however, also requires a lot of work from patients. “Activated patients” are expected to contribute data and information, and participate in “unobtrusive” monitoring, to make personalized medicine a reality. At the same time as more work is required from patients, their influence over how their data and information are used is waning. This stands in a tension with the rhetoric of patient empowerment and patient participation. Bringing together empirical work and critical scholarship from medicine, public health, social and legal studies, STS, bioethics, and digital sociology, this book analyzes the challenges of personalization driven by patient work (“personalization from below”). It proposes an understanding of personalized medicine that lets technological practices serve the needs and interests of patients instead of ruling them.