This chapter explores the different attitudes (or 'computational temperaments') that anti-war activists bring to their engagement with technologies. The distinction between 'hackers' and 'users', as drawn from the sociology of technology, is useful in this regard. What we see, empirically, is that UK anti-war groups have mainly displayed a user-oriented approach to technology, making use of the manifest functionality of new communication tools largely as intended by their inventors. Occasionally, however, a more innovative approach to communication technologies is evident. This more hacker-oriented approach is characterised by an irreverent attitude to the rules embodied in ICT devices, as individuals stretch and bend the functions of different devices and discover new ways to mobilise participants, reach audiences and coordinate protest. It is particularly where the pursuit of collective action requires horizontal communication structures that the hacker attitude may offer significant benefits.