Italy is a Johnny-come-lately to the peace movement that has swept the rest of Western Europe in the last year. But in a little more than two months, the peace issue has become so popular here that special-interest groups, from the labor unions to the previously uninterested Communist Party, have jumped on the bandwagon and are jockeying to control the movement.
''At this point, the peace movement in Italy is more a mood than a movement, '' said Massimo Teodori, a peacenik from the 1950s, now a Radical member of parliament.
''It's too early yet to know who will eventually utilize this mood.''
Unlike the movements in Britain, the Netherlands, and West Germany, the Italian peace movement did not gradually spring up from a strong pacifist tradition promoted by grass-roots religious organizations, intellectuals, and women's groups.
It is, Mr. Teodori says, ''a combination of spontaneity and political interests that has brought out hundreds of thousands'' into the streets all over Italy in the last six weeks.
A poll by the leftist Italian weekly, Panorama, last week found that 33.5 percent of Italians think a nuclear war is ''probable.''
Two months ago, the only people talking about peace in Italy were a handful of intellectuals and left-wing Roman Catholics and Radical Party members descended from the nonviolence movement of the 1950s.
And then, to everyone's surprise, a Sept. 27 peace march in Perugia drew between 30,000 and 50,000 people.
Soon after, the Central Committee of the Italian Communist Party, which had been holding back for fear of being condemned as a Soviet lackey or for switching to an anti-NATO position, decided to put its powerful, efficient organization behind the next march.
Approximately a quarter-of-a-million people turned out for the Oct. 24 peace march in Rome. Many of them arrived in the 12 trains and 400 buses provided by the Communists, who are generally getting credit for having given the peace movement a big push.
But old-time pacifists are loath to attribute - publicly, at least - the movement's sudden success to the Communist Party.
''The movement is purely spontaneous concern against nuclear war,'' said Ernesto Balducci, a Catholic priest.
And Giacinto Militello, leader of the communist-affiliated CGIL labor federation, said, ''The strongest organizer we have had for the peace movement in Italy has been Ronald Reagan. His announcements of limited nuclear war in Europe and the construction of the neutron bomb really woke people up here, particularly our young people.''