Contrary to a common picture of relationships in a market economy, people often express communal and membership-seeking impulses via consumption choices, purchasing goods and services because other people are doing so as well. Shared identities are maintained and created in this way. Solidarity goods are goods whose value increases as the number of people enjoying them increases. Exclusivity goods are goods whose value decreases as the number of people enjoying them increases. Distinctions can be drawn among diverse value functions, capturing diverse relationships between the value of goods and the value of shared or unshared consumption. Though markets spontaneously produce solidarity goods, individuals sometimes have difficulty in producing such goods on their own, or in coordinating on choosing them. Here the law has a potential role. There are implications for trend setting, clubs, partnerships, national events, social cascades, and compliance without enforcement.

People often engage in shared consumption experiences with other people, including romantic partners, friends, family, coworkers, neighbors, and acquaintances. Although the field of consumer psychology has traditionally focused on the perspective of an individual consumer, researchers are increasingly recognizing the importance and relevance of studying shared consumption (also known as joint consumption, dyadic consumption, or group consumption). In this chapter, we first discuss common methodological paradigms for studying shared consumption, given that studying shared consumption poses unique methodological challenges relative to studying solitary consumption. We then discuss prior research on shared consumption, organizing our review around the potential benefits and potential costs involved in shared consumption as compared to solitary consumption. Finally, we delineate four main areas for future research on shared consumption that we view as particularly promising.