Cross-border collaboration has become the rule for a growing number of enterprises in post-modern societies. In this context, constructing trust is directly related to establishing and maintaining strategic partnerships and alliances. This PhD project investigates the development and performance of trust between Greek and Turkish business partners in a cross-border collaboration setting. Trust is understood as a dynamic construct that operates mainly in the interactional order. It is perceived as a situated and negotiated accomplishment, something partners do in interaction either in institutional settings or in their everyday personal lives (Candlin and Crichton, 2013; Pelsmaekers, Jacobs and Rollo, 2014). The project adopts an ethnographic approach and seeks to capture the ways in which trustworthiness is understood, warranted and performed by participants. The study attends to the plea for more qualitative studies on trust and contributes to literature concerned with how trust develops and evolves over time in cross-border collaboration settings. The research data include 56 hours of semi-structured ethnographic interviews with business partners, and audio and video recordings of natural interaction, including formal meetings, dinners, visits and everyday talk. The data are analysed from an interactional, sociolinguistic perspective. Trust development in the data is intrinsically linked to perceptions of trustworthiness. The findings suggest that trustworthiness perceptions depend on the perceived expertise and morality of partners, which are then affected by social relationships, shared group membership and the interactional histories that these generate. Shared group membership emerges as particularly significant in the context of a specific case in the data. The analysis shows that by identifying with each other on the basis of shared attributes, in this case regional identity, partners can develop affinities and close personal relationships that facilitate the development of trust. The thesis offers insights also with regard to how trust is enacted in workplace discourse. The findings suggest that negotiation of business decisions during meeting talk constitutes a good arena for the study of trust, as it provides business partners with the opportunity to claim trustworthy personas for themselves through relevant positioning. The work adds to the literature on organisational trust from a discourse analytical perspective and its findings are relevant both to workplace discourse scholars and practitioners interested in workplace relationships.