Separate individual's disposition to take action does certainly not constitute a sufficient condition to engage in demonstrations. Doubtlessly, equal importance is due to organisational and institutional factors in society, and the individual's position in those. Ultimately, a demonstration is the result of a struggle between organizations for going control over individuals in order to support or defend their own objectives. In the mobilization process these organizations may make use of a diversity of mechanisms and techniques to control or to influence their members, as there are: the exploitation of the affective and instrumental ties binding the individual to the organization; the access to - and the use of - the mass-media; the use of selective communication by the organizational leaders and the induction of frustration. Special attention is given to the role of the militant and the characteristics of his language in the mobilization proces