Published by the" OE‌CD Reviews of Regional Innovation", this report analyses cross-border cooperation in the area of innovation, based on the study of six cross-border regions: Oresund (Denmark-Sweden), Helsinki-Tallinn (Finland-Estonia), the Bothnian Arc (Sweden-Finland), Hedmark–Dalarna (Norway-Sweden), Ireland-Northern Ireland, Top Technology Region/Eindhoven-Leuven-Aachen Triangle (Netherlands-Germany-Belgium). It addresses three core questions with respect to supporting innovation policy in cross-border regions: Why and when does it make sense to collaborate cross-border for innovation? How can public and private actors work together cross-border (governance)? What are the policy instruments for cross-border innovation collaboration? The online consultation of the book is free.