Rural communities that depend on common-pool resources for their livelihoods are being increasingly affected by the expanding global market system. Because such market integration is still relatively thin, communities vary in terms of market comprehension. Using a common-pool resource dilemma experiment, this study examines the effect of market knowledge on decisions concerning the use of common-pool resources among Borana pastoralists. Participants chose to use shared grazing rangelands at low or high levels of grazing intensity. Depending on the resource-use decisions in previous rounds, the participants encountered different pasture-availability conditions that required them to make trade-offs between their short-term interests and the long-term sustainability of the shared rangelands. The results indicate that, when resource conditions were good, resource users with more market knowledge are more likely to choose lower grazing intensity. During scarcity, this effect is weaker. The results further show that within-group variance in market knowledge has a negative effect on decisions relating to sustainable-resource use in times of resource scarcity. The results imply that providing an understanding of market functioning is of vital importance to protecting shared natural resources from depletion in communities experiencing increasing impact from the global market economy.