This paper focuses on the development of trust in temporary inter-organizational relations. One specific form of such relations is public construction projects established by competitive tendering. In this context, previous studies have suggested that the shadow of the future only moderates behavior to a limited extent and trust may seem hard to come by. The present in-depth case study adds to the theorizing of trust dynamics by demonstrating that reciprocal norms at the industry level, as well as reciprocal norms developing during project execution, contribute to the development of trust. The study connects trust, reciprocity, and actions, giving insight into the interplay between trust and reciprocity, the interplay between reciprocal norms at the industry level and the project level, and the role of small and large actions in the trust process.