After more than four decades of development activities, the world has witnessed both the intended and unintended consequences of development efforts, with results varying from country to country and even within national boundaries. While the benefits and positive results of development are shared and enjoyed by many, a large portion of the world population remains excluded from the fruits of development. Other problems such as income disparity, poverty, social and political exclusion and marginalization, human rights violations, armed conflicts, terrorism and social justice have in fact not been reduced but may have intensified in many cases. This manuscript is co-authored by three Thai economists with different backgrounds, and the content was first presented at the international conference on “Alternative Development and Sufficiency Economy”. The conference was held by the National Institute of Development Administration to celebrate the auspicious year of His Majesty King Bhumibol Adulyadej’s 80th Birthday Anniversary in 2007. Much beloved by the Thai nation, His Majesty the King has, throughout his reign of more than 60 years, through words and actions, suggested various alternative development concepts and practices, including “Sufficiency Economy”.