This chapter discusses the value of personal data from two complementary perspectives: the value of personal data for firms and the value of personal data for individuals. The chapter starts with a short introduction into the rise of personal data markets – markets basically driven by the economic exploitation of personal data. Then the chapter discusses how firms asses the value of personal data. This can be done from different angles, such as stock value and revenues. Another inroad is the costs of data breaches. A second perspective which is discussed is the valuation of personal data by individuals. Some empirical studies are presented that show how individuals value their personal data and what choices they tend to make. The chapter concludes with placing these developments in the frame of the upcoming data protection regulation. Data protection by default has relevance when taking the empirical studies seriously. © IFIP International Federation for Information Processing 2015.