This article analyses the normative dimension of metropolitan governance in the case of Montreal. According to the main schools of thought (the reform school, the public choice school, new regionalism and the rescaling approach), there is an ideal scale at which to achieve specific goals such as equality, efficiency, democracy and economic competitiveness. These ideologically oriented conceptions of metropolitan governance are assumed by actors and used as symbolic resources to build their own strategies, i.e. to support or contest institutional reforms — what we call the metropolitan trap. The case of Montreal, which underwent two successive institutional reforms between 2000 and 2006, provides empirical evidence for this idea. Our analysis reveals that the Government of Quebec and local elected councils of Greater Montreal are trapped by these normative conceptions, especially the old regionalisms. However, scalar strategies do not compete equally, as the institutional context legitimates specific approaches to metropolitan governance.