Growing interest surrounds how sustainable practices can be incorporated into a company's supply base. A growing stream of research has examined how companies can incorporate “green” criteria into their supplier selection decisions. This research focuses on a specialized supplier selection decision: transportation carriers. Trucking companies in particular are under pressure to reduce their environmental footprint and improve working conditions for their drivers. As such, the purpose of this research is to explore how carriers' environmental and social sustainability performance influence shippers' selection decisions and trust perceptions. Two scenario-based experiments were conducted to understand whether shippers incorporate the environmental and social sustainability performance of carriers into the selection decision. The carrier selection decision was characterized by a long-term arrangement in study one and a short-term arrangement in study two, and both studies controlled for the economic dimension so that the distinct effects of the social and environmental dimensions could be isolated. The results find that environmental and social dimensions of sustainability play differential roles in short-term and long-term carrier selection decisions, with environmental dimensions playing a more significant role in long-term selection decisions and social dimensions playing a more significant role in short-term selection decisions. The findings offer a more nuanced theoretical understanding of sustainable carrier selection decisions and practical guidance for practitioners and policymakers.