This study investigates the balance between forces of standardization and differentiation in the evolution of residential density in Canada's four largest metropolitan regions between 1971 and 2006. The leading factors of standardized development are the continentwide postwar adaptation of urban form to the automobile and growing housing space consumption. The influence of these factors is manifested in increasing convergence in the density levels of the four metropolitan regions as one moves from older to newer zones. Nonetheless, inherited urban forms, topography, economic and demographic performance, and land-use and transportation policies all have the potential to shape distinct density patterns. Each metropolitan region presents a specific density trajectory: Toronto registers a pattern that can be qualified as stable and recentralized; Montreal emerges as a decentralizing metropolitan region; Vancouver shows clear signs of intensification; and in Ottawa-Hull the trajectory combines decentralization and stability. These different metropolitan trajectories offer lessons for intensification strategies. Findings suggest that continentwide tendencies are shaped by features specific to each metropolitan region, and that successful intensification policies must build on those features. [Key words: density gradients, metropolitan regions, metropolitan trajectories, urban intensification, metropolitan planning.] This study investigates similarities and differences in urban development in the four largest Canadian metropolitan regions (labeled CMAs [census metropolitan areas] by