The paper analyses the relationship between the concept of trust-responsiveness and the activity of institutional design. This relationship seems particularly worth of investigation. While, on the one hand in fact, an high level of trust is necessary for the efficient functioning of organisations and markets, the underlying economic logic tends to erode the stock of trust present in those environments. Is such a paradox of trust that, leaving aside its intrinsic value, makes this topic of such a vivid interest and worth of deep investigation. We shall provide a definition of what trust, trustfulness and trustworthyness are. The limits of the traditional economic theory in accounting for the "phenomenon trust" will be stressed and some alternative models of explanation will be described, with particular emphasis on the model based on the idea of "trust-responsiveness". Given such a theoretical framework some of the conditions that affect the process of accumulation and erosion of the resource trust shall be explored. The tension between rules and trust turns out to be not inescapable, though it calls for a changing in the designing logic of those institutions. We shall discuss what are the changes needed in order to implement a trust-enhancing activity of institutional design.