Religion, and particularly the Catholic Church, was at the center of the emergence and initial mobilization of the pro-life movement in the United States. The movement originated in Catholic opposition to the liberalization of abortion law beginning in the 1950s, and accelerated rapidly after 1973 when abortion was legalized nationwide by the Supreme Court. Protestants began entering the movement in large numbers beginning in the 1980s, which corresponded with a peak in the amount of antiabortion street protest (and violence). All forms of pro-life protest—educational outreach to influence public opinion, political and legal involvement to influence the legal status of abortion, the development of crisis pregnancy centers to persuade individual pregnant women to carry their pregnancies to term, and direct action against abortion providers—have their roots in this formative period of movement mobilization, and all have continued to be important elements of the movement over the last half century. All these forms of protest activity include a religious component. They involve activists of deep religious faith, motivated by religious ideas, using religious principles in arguments about abortion, and depending on the leadership and resources of religious organizations. But the role of religion in the movement is sometimes overstated. Religion has not been the sole source of support for the movement. Pro-life protest has always included activists and organizations that are partially or wholly outside these strands of religious influence. Religion has also been a frequent source of tension and conflict in the movement, in addition to being a source of support. And the relationship between religion and the movement in recent decades does not distinguish it from the underlying partisan political landscape in which it is now firmly rooted.