Most discussions of Communities of Practice (CoP) place them in the context of a primarily internal-to-the-organization approach to managing knowledge. The construct, however, has application across the entire value chain of an organization, including the domain of a company's customers. This article explores the strategic value of building Customer Communities of Practice (CCoPs), learning networks among customers of a company whose win-win value proposition helps customers gain valuable insights from other peers while also providing the sponsoring company with a means to further innovation, loyalty and deeper insights into the markets they serve. The analysis suggests three types of CCoPs, including business to consumer, business to business, and communities of channel distributors. Case studies of each are presented and an especially extensive treatment is offered of the second type based on the author's experience of building a CCoP for his own software company. The discussion concludes with several lessons learned and practical guidelines for building successful CCoPs in any industry.