Social networking sites are becoming an increasingly important touchpoint in the consumer decision-making process. With communities on social networks, brands can influence consumers at various stages of the buying process, including loyalty-building. Research in this area has shown that with brand communities on social networks, businesses can build and strengthen relationships between all the building blocks of a brand community (product, brand, business, other consumers) and consequently build consumer loyalty. Brand community members on social networking sites are believed to be more loyal than non-members, but the question remains how and why relationships at different levels of communities on social networking sites are shaped and what role they play in building consumer loyalty. In my qualitative research, I focused on researching the role brand communities on social networks play in shaping consumer loyalty. I was also interested in how brand communities on social networking sites are connected to different forms of loyalty consumers develop in those communities. The empirical part has shown that in terms of community membership and loyalty shaping the most important building blocks of brand communities on social networks are product and brand. Consumers also highlight other consumers as important, and the company as the least important building block. Membership in a brand community can only contribute to loyalty in the presence of prior experience with the brand. In particular, it contributes to attitudinal loyalty more than behavioral loyalty. Among the forms of loyalty that dominate in these communities are those characterized by high personal determination.