The authors study consumer perceptions of firms that sell products designed by users. In contrast with the traditional design mode, in which professional designers employed by firms handle the design task, common design by users involves the firm's user community in creating new product designs for the broader consumer market. In the course of four studies, the authors find that common design by users does not decrease but actually enhances consumers' perceptions of a firm's innovation ability. This ¿innovation effect of user design¿ leads to positive outcomes with respect to purchase intentions, willingness to pay, and consumers' willingness to recommend the firm to others. The authors identify four defining characteristics of common design by users that underlie this innovation inference; namely, the number of consumers, the diversity of their background, the lack of company constraints, and the fact that consumer designers actually use the designed product all contribute in building positive perceptions. Finally, the authors identify consumer familiarity with user innovation and the design task's complexity as important moderators that create boundary conditions for the innovation effect of user design.