Most research on the security implications of environmental and demographic change does not explicitly distinguish between urban and rural areas. While statistical conflict analyses are increasingly sophisticated with respect to spatial and substantive disaggregation they largely ignore the possibility that urban and rural areas may be affected differently. In Africa, a continent assumed to be particularly vulnerable to the social and economic externalities of environmental and demographic change, less than one percent of the land mass is defined as ‘urban’. Yet, the population that lives in African cities is expected to increase by more than 150% between 2020 and 2050 according to UN population forecasts, massively outpacing rural population growth estimated at 35%. Given the vast social transformation associated with this process of rapid urbanization, understanding the dynamics and consequences of urban population growth in Sub-Saharan Africa, and its possible relationship with environmental factors is key to reducing vulnerabilities and facilitating sustainable urban growth on the continent. In this article we argue that high urban population growth may strain the provision of public services in urban areas, heighten competition over scarce urban land, and increase the chances of urban social unrest. We expect population pressure to have the most profound effects on social unrest in peri-urban areas, meaning the urban outskirts. We further investigate whether environmental push factors, operationalized as droughts happening in rural areas proximate to the urban centers, could be driving any effect of urban population growth on social disorder, possibly supporting concerns over climate change-induced social unrest. We test our expectations on a sample of similarly sized urban and peri-urban ‘grid cells’ covering the whole of the African continent for the 1997–2010 period, using geo-coded social unrest data. Our analysis shows that urban population growth is associated with increased unrest in the peri-urban areas only. We find no evidence, however, that this relationship is driven by environmental push factors in the form of nearby droughts. The study contributes insights relevant to the broader debates about possible security implications of hyper-urbanization and climate change.