This essay aims to analyse the main attitudes and concepts underlying the anti-militarism of the «new» Radical Party (Pr), and to outline the reasons that led the Radicals to embrace conscientious objection as a political objective. In the years 1961-1968, the Radicals elaborated their own anti-militarist position, picking up reflections and concepts from Anglo-Saxon anti-nuclearism and Italian pacifism. They aimed to overcome the positions of national neutralism in favour of a bilateral plan for conventional and atomic disarmament in Europe. At the end of the Sixties, the battle for the legal recognition of conscientious objection became a qualifying feature of the Pr. The Radicals identified the refusal to serve in the army as a fundamental right of the individual. A right that could powerfully contribute to the disruption of military structures and then to the dismantling of the «regime». The Radicals played a crucial role first in making such issue a salient one for the general public, and then in pressing the Italian Parliament to approve the conscientious objection law (Law 772) in 1972.