Relationships with work colleagues can mitigate job stress; this article proposes a new perspective on such effects, in accordance with social capital theory, to delineate the potentially distinct impacts of the two dimensions of relational and structural social capital. A partial least squares analysis of network data in a medium-sized company (N = 343) offers evidence of an effect of the relational dimension (tie strength), through social support. The structural dimension (bridging ties, i.e. whether an employee has social ties with members of other departments) reveals a dual effect involving reduced stress but also diminished social support, which can increase stress. These dual effects reflect the two levels on which bridging ties act, namely, cognitive (selfdistancing) and social (marginalization from the immediate work context) levels. Next, with two scenario-based experiments (N = 289 and 245), the authors manipulate bridging ties and gain further evidence of the proposed mechanisms. These findings highlight the social underpinnings of stress and the critical role of the structure, not just the quality, of work relationships. They also identify a dark side of bridging ties, which can enhance individual performance but also create the potential for negative wellbeing outcomes.