The idea that school systems should become self-improving is a growing trend internationally. Put simply, this involves the strengthening of links between schools so that they can provide mutual support and challenge. So far, however, there is little research that throws light on what is involved in attempts to introduce this approach for the first time. Drawing on its authors' privileged access over a 4-year period, this paper analyses what happened as one education system explored such a move. In particular, it looks at the challenges involved in strengthening collaboration between schools within policy contexts that continue to emphasise competition as a means of achieving improvements. It also examines the nature of the transitional arrangements that are required in order to move from existing organisational conditions to more collaborative ways of working. Drawing on lessons from these experiences, the paper concludes with a series of principles that are intended be useful to those in other policy contexts that are involved in introducing similar reforms.