This timely book is a comprehensive analysis of incomplete International Investment Agreements (IIAs), featuring insights from negotiating experiences in a number of bilateral and multilateral investment treaties. It examines problems, causes, and solutions surrounding this phenomenon by employing incomplete contract theory and opens new avenues in discussing how to correct incomplete IIAs. Throughout the book, the author challenges the fundamental assumption that most IIAs are concluded in a complete manner and emphasizes the importance of accounting for the fact that IIAs are often concluded without significant investment protection articles and are subject to renegotiation. Park applies various interdisciplinary approaches, including incomplete contract theory and development theory, to illustrate how countries easily postpone their treaty negotiations and are willing to renegotiate to remedy incomplete IIAs. Furthermore, he depicts the reality of treaty negotiation in recent years, helping readers to understand how countries are failing to negotiate complete IIAs and how utilizing an economics approach could analyse and resolve this issue. Offering a useful and practical contribution to the discussion on the resolution of incomplete IIAs, this book will be key reading for academics and researchers within the fields of commercial law, international economic law, trade law and international investment law. It is also a must-read book for both government officers and investment treaty lawyers in all countries involved with Free Trade Agreements.