The term \"soft power\" was coined by Joseph S. Nye Jr. of Harvard. The definition of soft power has expanded over the years and continues to grow. In most contexts, the United States is the focus of debate over its use of or lack of soft power and the appropriateness and positive or negative effects generated. In more recent times, China has had a diplomatic makeover and has begun utilizing its soft power capabilities. By no means is China able to surpass the United States soft power capabilities. As China's economy and influence in the region continue to grow however, China as an alternative to the United States can become a reality. This thesis's focuses on China's soft power in its relations with its Southeastern neighbors (Myanmar, Cambodia, Vietnam, Thailand, and Laos) and takes as a case study its impact on China's development plans for the Lacang-Mekong River. I determine how the utilization of soft power tools allows China to pursue its development plans with minimal interference from the other five riparian countries. The thesis is in four sections. They assess a) what is soft power and its tools; b) how China applies its soft power on its Southeastern neighbors; c) how this affects China's efforts to participate in development of the Lacang-Mekong River; and d) what the implications are for the United States?