Regional and national systems for sharing electronic health records have the potential to improve the quality of health care. However, their development and implementation have been hampered by competing organisational interests, complexity and controversy among users. we will use a framework that facilitates analysis of multiple contexts of use, and the different modes of argument used to promote and question new systems to compare five implementations in Australia and Britain. the aim will be to identify and investigate sources of delay and tension, as well as future opportunities for collaboration and progress. Outcomes will be applicable to other large public interorganisational systems that collect, share and use sensitive data.