This article provides an exploratory model that assesses the factors that influence formalisation of information systems (IS) for small- and medium-sized enterprises (SMEs) in sub-Saharan Africa drawing on data gathered in Botswana. The paper defines four levels of formalisation of IS for SMEs and identifies the internal and external factors that influence the process of IS formalisation. Key findings demonstrate a strong reliance on informal information practices amongst SMEs, alongside widespread unmet demand for formal information. It is also observed that successful enterprise development requires optimum use of both formal and informal IS. Evidence suggests this is achieved through developing the necessary internal capabilities and skills for information handling, including use of information and communication technology (ICT) and by forging key external market linkages – a duality of factors that constitute two key drivers for formalisation. The paper discusses the implications of the study for information systems in general and for the practice of information systems in SMEs in sub-Saharan Africa in particular.