This report aims at giving an overview of the emerging research field of open innovation in a phase that is still very fluid. The purpose of this report is to depict the major tendencies of publications through identifying the main themes in literature and investigating the research frontier. It also aims at discussing potentially important fields of investigation that are still left rather unexplored. This report builds on two main studies. First, a literature overview of the publications on open innovation published in key databases until November 20, 2007 was conducted. However, since the expression was coined as late as 2003, much ongoing research is still not found in the publications. In a second study, nine key researchers in the open innovation field were asked to define the frontier (from the UK, Denmark, France, Germany, Austria and the U.S.) in open innovation research. Their opinions were used as an additional input when trying to identify the future directions for research.