This chapter examines how Big Data has been used in policymaking and synthesizes the main strands of the emerging literature in this field. It first outlines the growing expectations surrounding the use of Big Data to support public policy, and discusses the key characteristics of Big Data. It then reviews how Big Data has been applied at different stages of the policymaking process and highlights both the opportunities and the limitations identified in existing studies. Building on these insights, the chapter proposes a data-driven EBPM approach that underpins the empirical analyses in the remainder of the book.