Why do we learn so much in school and university that we do not really need in life? What explains that so many chemists and engineers end up working as managers? This seminar introduces participants to sociological research on expertise and professions. We will focus on the strategies physicians, lawyers, and engineers use to claim jurisdiction over our health, property, and technology. By relying on case studies from the fields of medicine, law, and engineering, we will explore existing theories of expertise and discuss new approaches that may help us understand claims to expertise by programmers, designers, and other self-defined creative professionals.