Trust is a key feature of social interactions and central to interpersonal cooperation. Acts of trust are not only pivotal aspects of interpersonal cooperation and group cohesion, they also have important consequences for individual health and life expectancy. However, which social qualities of others foster trust, how individuals learn whom to trust, and how the brain integrates this information for optimal behavioral updating is yet unexplored. Here, I will outline two lines of research. On one hand, I will show the psychological and neural predictors of trust in different social contexts. On the other, pharmacological modulations of the neural brain structures involved in trust will be presented. In the first two behavioral experiments, I show that honesty functions as an antecedent of trustworthiness impressions and that an honest reputation is associated with higher trust during a future social interaction. Next, I delineate the neural signatures of these honesty-based trustworthiness impressions. Notably, similar to the behavioral effects of honesty on future trust decisions, I found that honesty-encoding brain regions predicted those future trust decisions, providing evidence of honesty-related brain regions that entail neural signal predictive of trusting behavior. Furthermore, an honest reputation also modulated neural responses to feedback information. Such neural modulation likely biases information integration during social learning. Consequently, I show in a further behavioral study that an honest reputation seems to indeed impair learning due to an honesty-dependent asymmetry in information weighting. Finally, I demonstrate how the pharmacological modulation of brain dynamics impacts trusting behaviors leaving trustworthiness impressions unchanged. On the one hand, these findings shed light on how honesty not only increases trust in others but also hampers learning processes for optimal behavioral adaptation. On the other, they provide the first pharmacological evidence of how impression-based trust can be changed without impacting those very first trustworthiness impressions. I finally propose accounts that might explain the observed behavioral and neural patterns and outline potential directions for new studies.