Word-of-Mouth Marketing—firms’ intentional influencing of consumer-to-consumer communications—is an increasingly important technique. Overviewing and synthesizing extant word of mouth theory, this paper shows how marketers employing WOM marketing methods face a situation of networked co-production of narratives. It then presents a study of a marketing campaign in which mobile phones were seeded with prominent bloggers. Eighty-three blogs were followed for six months. Findings indicate that this network of communications offers four WOM communication strategies—evaluation, embracing, endorsement and explanation. Each is influenced by character narrative, communications forum, communal norms and the nature of the marketing promotion. This new narrative model shows that communal WOM does not simply increase or amplify marketing messages. Rather, marketing messages and meanings are systematically altered in the process of embedding them. The theory has definite, pragmatic implications for how marketers should plan, target and leverage WOM and how scholars should understand WOM in a networked world. Kristine De Valck, Associate Professeur, Marketing Department, HEC Paris.