Organization theory suggests that structural change has disruptive effects on managerial behaviour and organizational outcomes, and that these effects are likely to emerge in the period between the announcement and the commencement of the new structure. We evaluate the validity of this argument by analysing the performance of English county councils in the transition period before the voluntary restructuring of a sub-set of these organizations. Disruptive effects are tested while controlling for a range of other variables, including the relative prosperity of the local population and the diversity of their service needs. The empirical results indicate that the performance of local authorities facing reorganization deteriorated prior to the onset of the new structures, and support the view that structural change has disruptive effects on organizational outcomes.