Internet commerce has transformed the marketing of goods and services. The separation between point of sale and seller, and the presence of geographically dispersed sellers who do not engage in repeated transactions with the same customers challenge traditional mechanisms for building the trust required for commercial exchanges. In this changing environment, legal rules and institutions play a diminished role in building trust. Instead, new systems and methods are emerging to foster trust in one-shot commercial transactions in cyberspace.The Article focuses on the rise of “social commerce,” a socio-economic phenomenon centered on the use of social media and other modes of social connection in electronic commerce. It identifies three mechanisms that are central to the development of trust in social commerce: communication and voluntary disclosure; barriers to entry; and community policing. These mechanisms simulate the characteristics of closely-knit environments, creating conditions conducive to trust. The Article describes these mechanisms in four new commercial settings: the sharing economy; next generation electronic commerce; online escort services; and online black markets in credit cards and controlled substances.