This paper draws upon symbolic interactionism in order to assess and discuss the findings from a longitudinal, single sector, case-based analysis of information system strategy (ISS) formation within two public sector institutions - institutions that are often characterised as bureaucratic in form, and culture. Each case acquired sought large, complex applications off-the-shelf that required customisation. These are discussed as configurational technologies. The research has been informed by differences in perspective about the nature of ISS formation as reported in the literature - with discussions of ISS often portrayed in bipolar terms; e.g. ISS as either planned or emergent. Literature suggests that the greater the sectoral stability, and the more oriented towards bureaucracy the institutional form, the more likely ISS planning will be formal - as opposed to emergent or evolutionary for example. First, an argument is presented against the logic of bi-polarity that is evident in many debates about ISS. Second, a case is made for the use of interactionist thinking as a means of better understanding the political processes that shape ISS formation. From symbolic interactionism, we utilise concepts of social worlds, trajectories, and boundary objects. Findings from the empirical study are presented, from which the discussion focuses upon the social shaping of trajectories, and the politics of configuration as constituents of the complex practice of ISS formation.