This chapter concludes that the book has presented evidence showing that technology and technical change are more flexible than generally allowed. The efficiency of different factors changes across countries and over time at different rates. Indeed, in some instances the efficiency with which one factor is used can decline while the efficiency of others increases. Since the 1990s, it has been increasingly clear that technical change tends to have a skill bias, but this book's findings reveal that nonneutralities are much more pervasive than that. They also occur across countries, and not just over time. Furthermore, they invest a broader set of inputs: not only skilled and unskilled labor, but also experienced and inexperienced workers, natural and reproducible capital, and a broad labor aggregate and a broad capital aggregate. The book has merely scratched the surface of the likely patterns of nonneutrality that exist across countries and over time.