This chapter introduces the reader to the wealth of evidence in this Handbook, and provides guidance for the interpretation of its findings. It first presents the basic definitions and delineations of innovation policy and discusses innovation policy rationales and their limitations. The chapter then reflects on the different understandings of policy instruments and on the nature of policy impact, highlighting the benefits, value and limits of impact analysis. Against this background, a typology of innovation policy instruments is presented which has been developed for this Handbook to systematise the evidence and which allows distinct entry points for readers interested in different kinds of instruments. After providing an explanation of the methodology applied throughout the Handbook, the chapter closes with reflections on how to interpret the findings of the book.