This study aims to investigated the influence of social commerce constructs and perceived usefulness on willingness to pay mediated by trust on the social networking site facebook.com in the city of Banda Aceh. This study uses a sampling technique that Nonpropability sampling and purposive sampling method used is the social networking site facebook.com in the city of Banda Aceh aged between 18-35 years. Analysis equipment PLS-PM and HLM used in this study to determine the direct and indirect effects of the variables involved. These results indicate that the constructs ratings and reviews have no effect on trust and willingness to pay users of social networking site facebook.com but other constructs such as forums and communities as well as the recommendations and referrals have effect on the trust and willingness to pay, and perceived usefulness have effect on trust and willingness to pay. The results also show the ratings and reviews do not have effect on willingness to pay mediated by trust, but forums and communities as well as the recommendations and referrals have effect on willingness to pay mediated by trust. The results also show majority value obtained on the relationship between variables by using analytical tools PLS-PM higher compared to using equipment HLM.