This chapter attempts to honor the chronology and evolution of ideas by referring to all the preceding contributions as elements of a resource mobilization perspective united by its differences from, and criticisms of, earlier approaches. The resource mobilization perspective quickly gained traction after the McCarthy and Zald article and Vanderbilt conference. The paradigm's maturation is evident in an edited volume appearing a decade later, whose contributions were about equally split between theoretical embellishments of the perspective and case studies of particular movements. In capitalist societies, the political and ideological systems attain at least a relative degree of autonomy from the economy, so they pose their own constraints and influences on social movement activity. Finally, the psychological readings of collective behavior were displaced by a political interpretation of social movements as power struggles over conflicting interests that shared many organizational dynamics with more institutionalized forms of conflict.