McCarthy and Zald (1973) argue that the more typical contemporary SMO is formally structured, with centralized, hierarchical structures and a clear division of labor and roles, and that the trend of SMs (in the United States) is towards greater professionalization of structures and leadership. ‘Classical SMOs,’ they explained, had part time, volunteer indigenous leadership and membership. In contrast, present-day SMOs are ‘professional SMOs’ because they rely on a small group of full-time leaders, ‘social movement entrepreneurs,’ who usually do not belong to the aggrieved group. These leaders are professionals from the new middle class who possess the necessary skills to lead SMs in contemporary
‘organizational societies’: they know how to deal with the state; they can create images and symbols and handle the communications media.