Based on recommendations of various international and intergovernmental bodies, many countries have adopted the concept of an Internet-based “Single Window” with an expectation that it would allow seamless G2G, G2B, B2G, and B2B information exchange within and across borders to enhance the facilitation of the international trade. The implementation of such effort requires unprecedented interagency collaboration which is seen as an unnatural act between non-consenting agents. To gain insights on how the interagency collaborative platform is established and maintained, we participate in the large-scale e-government project for trade and transport facilitation in Thailand, examine activities that have been carried out during the first phases, and assist the establishment of a collaborative relationship. From our study, we generate lessons learned that offer some practical ideas for policy-makers and project managers as well as issues for future research.