This paper calls for a re-specification of IT systems design and development practice as co-realisation. Co-realisation is an orientation to technology production that develops out of a principled synthesis of ethnomethodology and participatory design. It moves the locus of design and development activities into workplace settings where technologies will be used. Through examples drawn from case studies of IT projects, we show how co-realisation, with its stress on design-in-use and the longitudinal involvement by IT professionals in the 'lived work' of users, helps to create uniquely adequate, accountable solutions to the problems of IT-organisational integration.