Abstract
This study aims to examine the arrangement of regional cooperation agreements with third parties through the Build-Up System based on Indonesian laws and regulations, and how the parties regulate the rights and obligations of the parties in the regional cooperation agreement with third parties in West Nusa Tenggara through the Build-Up pattern This research is a normative study so that the approach used is the legislative approach and case approach. The results of the research show that the legal source of cooperation in the management of goods belonging to the region is Law No. 23 of 2014 concerning Regional Government, Government Regulation No. 50 of 2007 concerning Procedures for Implementing Regional Cooperation, Regional Regulation of West Nusa Tenggara Province No. 8 of 2007 concerning Management of Regional Property.