Many cultural products have the same non-rival nature as scientific knowledge. They therefore face identical difficulties in creation and dissemination. One traditional view says market failure is endemic ? societies tolerate monopolistic inefficiency in intellectual property (IP) protection to incentivize the creation and distribution of intellectual assets. This Paper examines that trade-off in dynamic, representative agent general equilibrium, and characterizes socially efficient creativity. Markets for intellectual assets protected by IP rights can produce too much or too little innovation.