With the raging trend of networking on social networking sites such as Facebook, almost all businesses are trying to reach their consumers using the social networking site. One way of promoting a company's products and services is by increasing the number of its Facebook page followers. We have studied DeLone & McLean’s model of IS success and have adapted it to the scenario of social networking sites, focusing particularly on Facebook. We have taken into consideration the dimensions of information quality and service quality and have studied their impact on consumer engagement and brand advocacy i.e. word of mouth. The proposed model provides quality dimensions that are hypothesized to influence consumer behavior in terms of their engagement and opinion giving. Results show that dimensions of information quality and service quality are important factors in molding consumer behavior accordingly and they partially effect consumer engagement which leads to brand advocacy.