This study investigated anionic surfactant LAS (Linear Alkylbenzene Sulphonate) removal processes in wetlands used for domestic wastewater treatment. The surfactant was monitored via a sensitive HPLC method or using radiolabelled techniques under controlled laboratory conditions, enabling a distinction to be made between primary biodegradation and mineralization. Hydrochemical parameters and enzyme activity (phosphatase, sulphatase and ~-glucosidase) were also assessed in several investigations. A field survey of three operational wetlands suggested that sub-optimal conditions occurred for LAS degradation with 55% removal observed. Climatological events influenced degradation with a springtime peak in LAS removal identified. Further laboratory investigation revealed possible controlling factors as temperature, pH and oxygen levels. However, effluent LAS concentration discharging from the wetland was stiJl low (min. 0.02mg L-1) and comparable to other sewage treatment studies. Biodegradation by biofilm microbial processes was identified as being the major LAS removal mechanism. Pre-exposure to LAS enhanced initial mineralization probably via adaptation of the microbial community resulting in faster kinetics and a shorter lag phase. Biofilm presence also slightly increased LAS adsorption. Plants were also identified as significantly enhancing LAS removal mainly via oxygen root release and supporting a more active and/or different microbial biofilm populations in comparison to that on the gravel. However, plant uptake, species and exudation of organic matter were insignificant. LAS at environmentally realistic concentrations did not impair natural wetland processes monitored, such as phosphate sorption, enzyme activity, plant growth, microbial activity and greenhouse gas emissions. Overall, the results of these studies support the hypothesis that LAS can be readily degraded in wetlands with similar removal processes involved as in more conventional sewage treatment processes. Hence this study suggests that constructed wetlands are a viable, cost-effective alternative for wastewater treatment for small communities in the UK and worldwide in facilitating LAS removal.