The ‘internet’—familiar shorthand for information and communication technologies (ICT)—is built on a physical infrastructure owned by a variety of state and private actors, foreign and domestic, with multiple interests. It has not only driven change on a global scale; its spread also had a profound impact on the social sciences. However, our understanding of how its architecture, and especially its owners, influence its political and economic impact is still in its infancy. This paper presents the Telecommunications Ownership and Control (TOSCO) dataset on ownership of internet service providers (ISPs) that allows to recognize the internet as strategically built and used by governments and corporations. Along with a thorough discussion of the conceptualization and operationalization of ownership as a variable, the TOSCO dataset enables comparative large-N analysis of the determinants and effects of varying ownership structures and identities in the transforming context of 49 African countries, 2000–2019. We demonstrate its usefulness with descriptive statistics and regression analyses using replication data from research on the internet’s democratizing and corruption-reducing effects. In allowing for a more realistic account, TOSCO supports scholars and practitioners concerned with the determinants and effects of internet service provision, use and control in Africa and beyond.