This research is the first to test the hypothesis that consumers face a “material trap” in which materialism fosters social isolation which in turn reinforces materialism. It provides evidence that materialism and loneliness are engaged in bidirectional relationships over time. Importantly, it finds that loneliness contributes more to materialism than the other way around. Moreover, it finds that materialism's contribution to loneliness is not uniformly vicious but critically differs between specific subtypes of materialism. That is, valuing possessions as a happiness medicine or as a success measure increased loneliness, and these subtypes also increased most due to loneliness. Yet seeking possessions for material mirth decreased loneliness and was unaffected by it. These findings are based on longitudinal data from over 2,500 consumers across 6 years and a new latent growth model. They reveal how materialism and loneliness form a self-perpetuating vicious and virtuous cycle depending on the materialism subtype.