The use of crowds to solve business problems, or to take advantage of market opportunities, appears to be increasingly popular. The impact of crowdsourcing across the marketing domain, suggests the importance of examining this phenomenon. Firms use crowds of consumers to perform many of the traditional tasks of marketing, such as choosing designs (e.g., Threadless t-shirts), testing offerings (e.g., Microsoft), creating promotions (e.g., Facebook), and determining pricing (e.g., Travelocity). To more effectively harness the power of crowds and to learn from crowds, firms should understand their capacity for absorbing crowd contributions and the motives underlying the participation of the crowd as well as their own participation. An eclectic review of the literature offers a base for distinguishing crowds using a range of motives from intrinsic to extrinsic. Exploration of these dimensions results in a propositional inventory identifying motivations for both crowdsourcing and crowd participation. These inform practitioners of consequences of crowdsourcing decisions and offer future research directions.