Alien invasive cacti are becoming a serious pest in Windhoek. Efforts at controlling them up till now have concentrated on manual clearing, largely driven by a volunteer organisation called Cactus Clean-up. This has made significant strides towards clearing particular areas of the hills in Windhoek, and at the same time raising awareness about the threats posed by cactus plants, but this method is expensive, it disturbs the soil and it can never achieve complete control of the problem because the cacti are very successful at regrowing from small fragments, and certain areas where they occur are inaccessible. Also, the efforts to organise and pay workers depend on the dedication of a few individuals, so this is not a lasting solution. Chemical control methods carry pollution risks and are also very expensive. Biological control has been used elsewhere (e.g. South Africa, Australia) in situations very similar to the one in Namibia - same invasive species, similar environments - with very high rates of success. Importantly, there have been no cases where introduction of the control agents have caused unexpected problems to the indigenous flora or ecosystem. This project intends to use the expertise and facilities available in South Africa and elsewhere, to introduce biological control agents against three species of cacti in Windhoek. The project is proposed by the Namibian Chamber of Environment (NCE), the Botanical Society of Namibia, and the Centre for Biological Control (CBC) at Rhodes University in South Africa. It is supported by the National Cactus Biocontrol Committee, which includes representatives from government (MET and MAWF), the Windhoek municipality, and the Namibian University of Science and Technology. This Environmental Assessment was commissioned by the NCE to obtain an Environmental Clearance Certificate for the project.