This chapter is concerned with environmental decision making in tropical seaport development in Vietnam. This small country has a long coastline of more than 3,000 km, and over 1,000,000 km2 of coastal waters, a factor which has encouraged development of maritime transport infrastructure to support economic growth. Environmental decision making is a process that integrates environmental assessments into the decision making process. Good environmental decision making processes identify pertinent environmental and social systems and decision options that keep the systems within acceptable damage levels, and allow people the freedom to choose among decision options according to present goals, values, perceptions and beliefs, while not jeopardizing future sustainability.