Social movements are defined as population groups with which people identify without the necessity of becoming a member of a formal organization; the collective experience is derived from common political goals and from collective behavior. Adherents of the anti-nuclear, peace and feminist movements are identified with survey questions of a three-wave electoral study of 1987 which allows the application of Rasch scaling to construct movement affiliation. The measures for the three movements predict the strength of support for the respective movements’ goals quite well, especially well if mobilization was high as for the anti-nuclear movement at that time. Movement organization is measured by types of ego-centric networks of supporters of the anti-nuclear movement. A distinction is made between strong and weak ties, the latter ones identified by relationships to adherents of the anti-nuclear movement beyond the people with whom one discusses important matters most frequently. Only these latter ties are good predictors for participation in demonstrations. By contrast, vote intentions for Greens or SPD vs. CDU or FDP depend on strong ties, that is the presence of movement supporters among one’s frequent discussants: The more are present the stronger one’s own affiliation which influences vote intention.