In this dissertation, I propose that trust is an important yet under-studied concept in supply chain relationships both upstream in a Business-To-Business (B2B) context and downstream in a Business-To-Consumer (B2C) context. In the first essay, I investigate the evolution of trust in buyer-supplier relationships in a VMI setting. Supply chain management literature is rich in pointing to the benefits generated by collaborative supply chain arrangements, however recently the dark side of these collaborative relationships has been reported as well. To the best of our knowledge, our study is the first to bring in a new dimension - "length of the relationship" to these research models. Using survey data collected from distributors that use VMI, we find that longer relationships are associated with lower levels of distributor trust in the manufacturer. This erosion of trust over time is fully mediated by the distributors' experience of psychological contract violation. Our findings demonstrate that good inventory performance may not be sufficient to maintain trust in VMI relationships, but regular communication between parties, as well as nonverbal documented agreements, may also be needed to maintain trust.

In the second part of the dissertation, I study the effectiveness of third-party trust seals that have emerged as a prominent mechanism to enhance trust in B2C online markets. Despite their common use by practitioners, systematic research studies of the effectiveness of trust signals are scarce. Exploiting a unique dataset of over a quarter million transactions across 493 online retailers, this study empirically measures the value and effectiveness of trust seals on the likelihood of purchase by shoppers. The dataset is collected from a randomized field experiment by a large trust seal provider, which enables us to infer the causal impacts of the presence of a trust seal. It is found that the presence of the online trust seal increases the odds of completion of purchase. I further find that online trust seals serve as partial substitutes for both shopper experience and seller size, which makes the seal more useful for first time visitors at a web site and also for smaller online retailers. Interestingly, the effect of the number of trust seals is subject to diminishing marginal returns, such that the presence of additional seals does not necessarily increase cart completion rates.