Previous research suggests that insufficient differentiation of organizations occupying central positions in an organizational field increases the possibility of a status quo threatening institutional change. Directly testing the relationship, the present study reveals a more complex picture of the linkages between organizational differentiation and institutional change. Drawing on developments in British politics, our study demonstrates that when the differentiation dimension of left-right politics was on decline, perceived differentiation of the major parties, instead of decreasing, increased audience support to a status quo threatening- electoral institutional change from FPPS (First Past the Post System) to PR (Proportional Representation). We further observe in a counter-intuitive manner that the increase in audience support to the electoral institutional change from FPPS to PR, however, weakened with the passage of time. We use both qualitative and quantitative evidence from the context of British politics to support and test our theoretical arguments. In particular, we found support for our theoretical hypotheses in analyses of data from British Election Surveys during the period from 1987 to 2001, which enabled direct measurement of the perceived differentiation of the two central parties (i.e., the Conservatives and the Labour) in British politics along the differentiating dimension of left-right politics and the voter support for an electoral institutional change from FPPS to PR.