The justification for creating temporary monopolies through patents and copyrights is that they encourage creative activity that would not otherwise take place. But Raustiala and Sprigman argue that imitation -- which music labels and movie studios often consider theft -- frequently stimulates creativity rather than discouraging it. In this engaging text, the authors draw on the experience of many industries -- fashion, cuisine, finance, and open-source software, among others -- to demonstrate that a lack of effective copyright protection hardly throttles innovation and in fact encourages it. They draw a distinction between “pioneers,” who develop significant new designs or formulations, and “tweakers,” who make incremental improvements in new concepts and who would be inhibited if intellectual property rules were more tightly drawn and enforced. Traditional music labels have decried the copying of recorded music, arguing that it discourages the composition and performance of new music. According to the authors, that is simply not the case: it is the traditional business model of the labels that is under threat, not the production of music. And copyright was conceived to protect creative activity, not particular business models.