Drawing from a sample of two roadside settlements in Tanzania, this paper examines the sustainability of pastoral livelihoods in these locations. It notes that in recent decades the centuries-old balance between pastoral systems and nature has become unviable due to gradual erosion of access to land and water. In addition, changes in lifestyles, coupled with the impact of education, economic pressure, environment and social interaction between pastoral and non-pastoral communities, have all contributed to the changes in the pastoral ways of life. In response to this, pastoralists are increasingly diversifying their livelihoods both within their traditional homelands and in distant areas. This diversification has necessitated changes in pastoralists’ settlement patterns. One such a change has been the migration into roadside settlements where, in addition to livestock-keeping, they also engage in non-pastoral activities. Findings reveal that migrant pastoralists have maintained their tendency to rebuild the livestock herds, and with increased number of livestock, environmental degradation, though at the moment localized, poses a threat to the sustainability of their livelihoods. Therefore, although pastoral livelihoods have been diversified, in the long run they are far from being sustainable. This is largely due to the threat that increased livestock pose to the environment, and some policy failures to address the problems of the pastoralists in general.