Consumer-to-Consumer (C2C) e-marketplaces cannot survive without participations from both a large number of buyers and sellers. Prior research on trust in e-commerce is mainly conducted from the buyers’ perspective. Combined with TAM constructs, this research explores the relative impacts of trust in terms of trust in market-maker and institution-based trust, and risk on individual’s transaction intentions in C2C e-marketplaces from both buyers’ and sellers’ perspectives. The results suggest that the major determinants of transaction intention in e-marketplaces differ between buyer and sellers. Perceived risk is found to have a stronger effect on sellers’ intention than on buyers’ intention to transact in e-marketplaces. In addition, we found that perceived usefulness influences only buyers’ transaction intention, whereas institution-based trust and perceived ease of use influence only sellers’ transaction intention. This study contributes theoretically to C2C e-commerce research and has practical implications for C2C e-commerce practitioners.