Across the last fifty years there have been huge efforts to construct more accountable institutions at every level from international organisations to state bureaucracies, from giant corporations and NGOs to small businesses and local charities. A principal instrument in seeking greater accountability has been an extension of law and regulation: more enforceable rules constraining more institutions and their office holders in more of their activities. Yet accountability by regulation has often disappointed. I shall argue that the principal problem is not that rules do not matter: they are evidently needed for the rule of law, and hence also for the protection of human rights, for democracy, and for commercial life.However rules are always and unavoidably incomplete and indeterminate. Their use is always a matter of judgement, and it is an illusion to imagine the rules can go ‘all the way down’. Yet contemporary regulation often appears to ignore this well established point. Small wonder that those working in the institutions are so often reduced either to putting excessive efforts into mere compliance—or to cynicism and gaming the system. A more adequate approach to institutional life would recognise the importance of institutional cultures that acknowledge the importance of institutional life being guided by purposes, standards and cultures that require and foster the exercise judgement in the use of rules.