This collection examines a key new development in the contemporary marketing landscape, the relationship between the informal exchange of information and advice among consumers – known as word of mouth (WOM) – and emerging social media. Whereas WOM has been around since as long as people have engaged in conversations, its transmission is no longer limited to face-to-face interactions over the clothesline and across backyard fences. Today, the dissemination of WOM through online channels such as Facebook, Twitter, LinkedIn, YouTube channels, blogs, and consumer forums has significantly altered the alacrity by which product and service messages are spread across a dramatically expanded consumer audience. As marketing practitioners have come to recognize the power of online WOM in terms of its impact on consumer beliefs, attitudes, and purchasing behavior, effective strategies for leveraging the consumer conversation require greater insight and understanding of WOM and social media. Towards that end, this book offers ground-breaking research from an impressive array of internationally renowned marketing researchers on the nature and dynamics of WOM transmitted through social media channels, advancing our understanding of consumer influence, which to date has largely focused on offline WOM. Among the topical issues covered are best practices for marketing practitioners, the conversational nature of online WOM, the dynamic interplay between online and offline WOM, WOM measurement and monitoring, and cross-cultural influences on WOM. This book was originally published as a special issue of the Journal of Marketing Communications.