The open source (OS) movement allows us to re-vision corporate branding from a corporate to a coproducer perspective. Corporations own their brands and unilaterally determine their positioning and evolution. Power and control are centralized and hierarchical: producers produce brands, which customers then consume. With OS, power and control are radically decentralized and hierarchical: producers and consumers coalesce into “prosumers.” The authors introduce marketers to the OS phenomenon and develop a typology of brand aspects that can be “open” or “closed”: physical, textual, meaning, and experience. The authors elaborate new dimensions for brands and revisit the functions that brands perform and link these to the evolutionary trajectory of branding, arguing that OS represents a final phase in the evolution of corporate brands from closed to open brands. The article concludes with a research agenda.