MECHANISMS OF COALITION FORMATION: VENUE SHIFTING IN THE ABORTION RIGHTS MOVEMENT BEFORE ROE V. WADE^*

Research suggests that coalitions between social movement organizations (SMOs) are more likely under conditions of perceived political opportunity. But what are the mechanisms of this effect? Extant research suggests resource-need, collective-benefit, and emotional mechanisms. Here, I theorize a venue-shifting mechanism. When an SMO switches to a new political venue to pursue a perceived political opportunity, it lacks the specific resources necessary for success in that venue and seeks them from another SMO. Drawing on primary and secondary historical data, the article demonstrates this mechanism in the coalition behavior of the National Association for Repeal of Abortion Laws (NARAL) before the 1973 Roe v. Wade decision that legalized early abortion on request in the United States.