Cet article analyse les conditions associées au développement de la relation de confiance entre les gestionnaires et les représentants syndicaux au sein d’entreprises qui ont adopté des innovations de différentes formes. Nous nous intéressons à la confiance entre des agents qui interviennent au nom de commettants. Notre étude démontre que si le développement de la confiance bénéficie d’un climat de travail moins conflictuel, d’autres conditions sont également requises, particulièrement le partage des informations entre les parties. Par ailleurs, un contexte de transformation peut améliorer la relation de confiance, particulièrement lorsqu’un processus participatif confiant un rôle au syndicat est adopté pour introduire les innovations. Celles-ci peuvent ainsi favoriser le développement de la confiance cognitive entre les parties, tout en respectant des intérêts spécifiques à chacune.This article examines the development of relationships of trust between managers and union representatives in a context of social innovations. Trust acts as a social lubricant and thus plays an important role in social relations within organizations undergoing change and which depend more on cooperation. However, trust is a multidimensional concept that appears in various forms that can be dichotomized between cognitive trust, which is based more on knowledge and reason, and identity-based trust, which is more emotional and may even involve holding common values. Within organizations, studies of trust have most often examined relations between workers and managers, or even members’ trust in their organization. Few studies have examined the relationship of trust between employers and unions. However, the interactions between institutional agents at work tend to encourage the development of the cognitive dimension of trust rather than its identity-based dimension. While encouraging cooperation between these agents and leading them to develop new relationships outside the traditional institutional framework, innovation nevertheless conceals two essential conditions for the development of trust: the interdependence of actors, and risk in the face of the future and unknown behaviour of their counterpart. Trust is not a given, but is rather a social construction that develops through the interactions of the actors at work according to the diverse conditions that we will examine.The data come from a study on new work relations between employers and unions. The sample includes union representatives and managers in goods and services firms that adopted different kinds of innovations. One thousand firms, each with more than 50 workers, were included in the study. A total of 242 union representatives and 221 managers returned their questionnaires. The sample was generally characterized by medium- or large-sized firms with a high proportion of male workers occupying permanent positions and with several years of seniority. However, there are differences between manufacturing sector firms and services sector firms. The latter employ more women who ...