This research investigates how the amount of trust a consumer has in an electronic commerce intermediary and the amount of expertise that consumer needs to acquire in order to be able to use the intermediary affect the intention to adopt the electronic commerce intermediary. The paper analyzes both the direct effects of trust and expertise on adoption intention, as well as the indirect effects through two mediating variables widely used in adoption studies, usefulness and ease of use. These effects are hypothesized to be further moderated by the level of transaction complexity. The results partially support both the direct effects model and the indirect effects model, pointing out that trust and expertise are, as hypothesized by academicians and practitioners alike, important in encouraging adoption of electronic commerce technologies. In addition, the results show that trust and expertise become more important in determining the adoption intention as transaction complexity increases.