The 1960s-era, Nashville nonviolent civil rights movement—with its iconic lunch counter sit-ins—was not only an exemplary local movement that dismantled Jim Crow in downtown public accommodations. It was by design the chief vehicle for the intergenerational mentoring and training of activists that led to a dialogical diffusion of nonviolence praxis throughout the Southern civil rights movement of this period. In this article, we empirically derive from oral-history interviews with activists and archival sources a new “intergenerational model of movement mobilization” and assess its contextual and bridge-leading sustaining factors. After reviewing the literatures on dialogical diffusion and bridge building in social movements, we describe the model and its sustaining conditions—historical, demographic, and spatial conditions—and conclude by presenting a research agenda on the sustainability and generalizability of the Nashville model.