Brand communities and social media often overlap. Social media is an ideal environment for building brand communities. However, there is limited research about the benefits and consequences of brand communities established on social media platforms. This study addresses this issue by developing a model depicting how consumers’ relationship with the elements of a brand community based on social media (i.e. brand, product, company, and other consumers) influence brand trust. The findings include that three of the four relationships positively influence brand trust. However, customer-other customers’ relationships negatively influence brand trust, which is counter intuitive and interesting. The prominent role of engagement in a brand community is also investigated in the model. Community engagement amplifies the strength of the relationships consumers make with the elements of brand community and it has a moderating effect in translating the effects of such relationships on brand trust. Finally, theoretical and managerial implications are discussed.