This paper reports research conducted in collaboration with the Hunt Museum, Limerick, Ireland, which examined how children's interaction in museums could be augmented through co-operative design. The paper describes the participatory design process that was undertaken over a two-year period, involving key informants and stakeholders, including teachers, docents (specialist museum guides) and curators. The designers also explored the potential of ubiquitous computing to enhance children's interpretive experience in museums, and this is also described. The research reported in this paper was supported within the EU disappearing computer (DC) initiative, specifically the SHAPE project. The goal of SHAPE, Situating Hybrid Assemblies in Public Environments, was to explore how emerging, novel computer technologies could be deployed in public spaces to enhance interaction and learning. The project culminated in the deployment of an innovative, large-scale computer-augmented exhibition, Re-Tracing the Past, in the Hunt Museum. This novel exhibition was open to the public from 9 to 19 June 2003. This paper documents the design process from initial scenario elaboration through to final deployment of novel technology in the museum. Evaluation data are also discussed, and the paper concludes with some insights for participatory design of technology to enhance children's interaction in museums. Furthermore, the review of evaluation data illustrates how the design themes that informed the extensive design process were successfully embodied in the final exhibition in the museum.