Waste water treatment is a problem that has plagued man ever since he discovered that discharging his wastes into surface waters can lead to many additional environmental problems. Strategies for control of water pollution have focused mainly on implementation of expensive and energy intensive conventional treatment technologies. The limited successes of such strategies can be attributed to the high capital investment requirement, continual replacement and high operation costs. In recent years, constructed wetlands systems have emerged as a low-cost higher forming waste water treatment technology compared to conventional treatment systems. There is a growing interest to develop and adopt this technology for water pollution control in India as well. This paper gives some introductory information on the concepts, pollutant removal mechanisms, engineering design, construction, vegetation and applications of constructed wetlands for waste water treatment.