Social commerce is growing as a new critical hub of product sourcing for both businesses and individuals. It has become an important strategy that helps companies, especially small and medium enterprises (SMEs), to connect with customers and to gain competitive advantages. Still, there is a scarcity of frameworks for evaluating social commerce system success and identifying what significantly contributes to success. This study aims to investigate the determinants of social commerce system success in the context of Thai SMEs. A questionnaire survey was conducted to evaluate the proposed model. The empirical results provide support for the relationship among six dimensions of the proposed model. System use and user satisfaction relate significantly to the success of a social commerce system, which is measured in terms of organizational benefits. Three factors associate positively to system use, namely system quality, service quality, and trust, all of which lead to user satisfaction. Further research can investigate other social factors or empirically test the model at different levels of success.