Drawing upon social capital theory and the platform synergy perspective from systems theory, this study develops an explanatory model to explain how social capital, platform synergy and active participation affect consumer benefits in an online group buying (OGB) context. Data gathered from OGB consumers through a large-scale online survey is used to test the hypotheses. The conceptual model was validated using the partial least squares (PLS) technique. The results show that (1) the consumer benefits created by engaging in OGB are contributed collectively by social capital (i.e., social interaction ties, trust, and value of sharing), active participation and platform synergy; (2) the social capital enhances consumer benefits by increasing consumers’ active participation; (3) the OGB platform synergy has a positive impact on social capital, active participation and consumer benefits. Our findings highlight the important role of active participation in mediating the effect of social capital and platform synergy on OGB consumer benefits. The results provide insights into (1) how OGB platform developers can provide synergic functionalities that are compatible to OGB activities to enhance consumers’ capabilities and the efficiency of OGB processes; (2) how OGB managers and initiators can leverage platform synergy to enhance social capital and the mediating role of OGB consumers’ active participation in exchange resources within the OGB community, thereby leading to effective consumer benefit creation. 
Consumer benefit creation in online group buying: The social capital and platform synergy effect and the mediating role of participation