This Article reports the first experiment to demonstrate the existence of a valuation anomaly associated with the creation of new works. To date, a wealth of social science research has shown that the least amount of money that owners of goods are willing to accept to part with their possessions is often far greater than the amount that purchasers would be willing to pay to obtain them. This phenomenon, known as the endowment effect, may create substantial inefficiencies in many markets. Our experiment demonstrates the existence of a related “creativity effect.” We show that creators of works value their creations substantially more than do both potential purchasers of their works and mere owners of the works. The creators in our study valued their works (in this case, paintings) more than four times higher than potential buyers did and almost twice as high as did owners of the works. Further, we provide evidence that these differences are the result of creators’ irrational optimism about the quality of their works. We conclude by discussing the implications of these findings for intellectual property (IP) theory in general and IP licensing in particular. Our findings challenge the classical economic approach to IP rights, and they suggest that IP markets may be less efficient than previously recognized.