This paper examines how land management systems have evolved as a result of different migrant groups moving into the Usangu Plains. Several factors have caused these migrations including climate, famines, search for arable and grazing lands, gainful employment, drought and dryland degradation. Findings from the study indicate that migrations into the study area have been more pronounced particularly beginning in the 1970s. This has involved both pastoralists and crop cultivators. The movement of people from different agro-ecological environments into the Usangu Plains has had some effects on the livelihoods of the people and the environment in the area. One of the impacts has been increased pressure on land that has led to decreased fallow periods and consequent decline of soil fertility, and changed land management systems that included introduction of new crops into the area, and intensified irrigation agriculture. Another implication on the environment is that the heavy in-migration of livestock and people into the area, combined with the extension of irrigation areas has created a shortage of grazing land. The consequent grazing in farmlands result in trampling that leads to soil compaction, thus limiting groundwater recharge. Thus it may be of interest to undertake more detailed studies on the effects of environmental changes particularly as they affect agriculture and people's livelihoods.University of Dar es Salaam