This research examines whether siblings and friends resemble each other in supportive behavior. Using a Dutch national sample of 6,289 individuals containing 12,578 relationships with siblings and friends, we investigated the relative importance of gender composition, geographical proximity, relationship quality, and contact frequency for support exchange with siblings and friends. Results show that, controlling for other influences, siblings exchange more practical and less emotional support. High relationship quality and contact frequency are positively related to exchange of emotional support with siblings more than with friends, as is--unexpectedly--living further away. Fewer differences exist in practical support exchange. In conclusion, siblings and friends are similar with regard to practical support but different when it comes to emotional support. (Contains 4 tables.)