Contemporary companies work in complex environment comprising many simultaneous running projects, i.e. multi-project settings. To a large extend those projects are interdependent and are multi-professionally constituted of representatives from customers, suppliers, other business partners and researchers from academia. The success of projects, particularly in the multi-project setting, is dependent of the collaboration and interaction among those actors involved. The aim of this article is to explore the dynamics of interactions with external actors, such as customers, suppliers, other business partners and academia and investigate the effect of interactions on performance in multi-project settings.

The methodology is based on a mixed-method approach, comprising a quantitative survey and a complementary case study. The quantitative survey questions are based on the extended literature study of project management interactions. The case study was selected in order to create a deeper understanding of the processes of interaction, barriers to interactions and the outcome in terms of project performance. The results show that interactions with external actors positively influence performance in terms of estimated quality, time, and cost, innovations and actor satisfaction.