The management of natural resource systems that span an international border is often complicated by a lack of coordination and communication between the stakeholders who are responsible for their stewardship. In some areas, stakeholders have taken a collaborative approach to managing these transboundary resources. However, effective transboundary collaboration can be difficult, as the presence of an international border often intensifies the barriers to the development of a collaborative process. This study highlights the experiences of eight collaborative efforts operating across either the U.S.-Canada or U.S.-Mexico borders. The lessons distilled from these efforts are intended to inform general transboundary practitioners, as well as those agencies and organizations that are working to develop a transboundary effort in the Flathead River Basin of Montana and British Columbia.