Recent advances in artificial intelligence (AI) highlight its potential to affect productivity, growth, inequality, market power, innovation, and employment. In September 2017, the National Bureau of Economic Research held its first conference on the Economics of AI in Toronto. The purpose of the conference and associated volume is to set the research agenda for economists working on AI. The focus of the volume is on the economic impact of machine learning, a branch of computational statistics that has driven the recent excitement around AI. The volume also highlights key questions on the economic impact of robotics and automation, as well as the potential economic consequences of a still-hypothetical artificial general intelligence. The volume covers four broad themes: AI as a general purpose technology; the relationship between AI, growth, jobs, and inequality; regulatory responses to changes brought on by AI; and the effects of AI on the way economic research is conducted. In highlighting these themes, the volume provides several frameworks for understanding the economic impact of AI. In doing so, it identifies a number of key open research questions in a variety of research areas including productivity, growth, decision-making, jobs, inequality, market structure, privacy, trade, liability, political economy, econometrics, behavioral economics, and innovation.