This study begins to fill the gap in sociological literature on movements and countermovements by exploring the dynamic environment of two movement organizations. After documenting the climate of public opinion on abortion, it investigates the strategy and tactics employed by a movement to maintain that opinion and a countermovement to reverse that opinion. It relates social movements to their social environments, social change, opposition, and strategy and tactics. It illustrates the efficacy of single-issue groups in the American social and political environment. Finally, this thesis demonstrates the validity of exploratory studies by uncovering elements of social movements and countermovements that had not been previously investigated.