This study explores the process by which trust evolves over time. There have been a number of studies underscoring the importance of trust in the online environment. However, most trust studies have concentrated on the initial trust, and there is little known about how trust beliefs evolve over time. The dynamics of trust are of particular importance in the use of infomediaries (online information providers), among which health infomediaries are the most important for Web consumers in dealing with their wellness and health issues. We investigate the evolution of trust using the case of health infomediaries. The examination of the temporal changes in trust was carried out through two approaches--comparative statics and dynamic analyses. The research method was laboratory experiment and the data were collected for two episodes of encounters. Two comparative statics models and one dynamic model were estimated in order to examine the parameter changes from one episode of encounter to the next as well as the dynamics of belief changes. The results of analysis show that the structure of trust changes over time and information quality becomes the single most important antecedent in infomediary trust building in the later stages of use. Furthermore, our study also indicates that satisfaction plays an important role in changing Web customers' trust beliefs. Contributions as well as research and managerial implications are discussed.