Abstract. Full Text is available at: https://www.emerald.com/insight/content/doi/10.1108/ITP-12-2013-0218/full/www.ncbi.nlm.nih.gov/pubmed/19142294Purpose This paper presents a work-centred study of how information systems practices and tools become shaped by their context. The purpose of this paper is to increase the understanding of how practices and tools co-evolve, with a specific focus on the role of context, and based on this to offer relevant design implications. The empirical motivation comes from attempts to utilize information and communication technologies (ICT) in resource-constrained settings. Design/methodology/approach Empirical work was conducted in primary healthcare facilities in Tanzania that offer Prevention of Mother-To-Child Transmission services. Four health facilities with different organizational and socio-economic characteristics were studied using ethnographic methods (participant observation, interviews and document analysis). The authors have employed activity theory as the theoretical framework, since it explicitly places human activity within a cultural, social and temporal (developmental) context. Specifically, the concept of mediation breakdown was used for data analysis at activity, action and operation levels. Findings By focusing analytically on situations of mediation breakdown in the situation of use, at both an activity, action and operation level, the authors have achieved an understanding of how information tools are being adapted to both their contextual conditions and the information needs of the community of users. Research limitations/implications The study illustrates the decisive role that context may play in shaping the actual usage of information technology. While the detailed findings were specific to the concrete domain, time and place, in general, an increased awareness of the role of context may lead to more robust approaches to the introduction of ICT solutions. Originality/value While activity theory literature offers insight on how to analyse context, the discussion is limited to the understanding of how context can be modelled into artefacts. The paper suggests that the contradiction concept is useful for studying the role of context and its impact in co-evolution of work and information tools. The study also contributes to the discourse in health information systems in developing countries by emphasizing the crucial role of the front line health workers’ own problem solving, invention and adaptation of information tools.