College students who supported opposing positions on abortion were asked to state their reasons for and against their own position as well as their reason for and against the opposition. Students then served as judges on 4 cases in which women were seeking an abortion. The circumstances motivating a woman varied across the 4 cases. Case information either challenged or supported prototypic assumptions and beliefs that underlie a prolife or prochoice stance. Students who received information directly challenging their position on abortion changed stances more frequently than those who did not. Three additional factors also predicted changes in stances: (a) taking a prochoice rather than a prolife position, (b) being able to cite more problems with one's own position, and (c) receiving challenging cases that present novel rather than anticipated conditions motivating a woman's desire for abortion. The results are discussed in terms of a process model of conceptual change and learning, where changes in stances come about because of awareness of new information about the harms and benefits of each position, which in turn causes a shift in the relative ranking of important moral tenets that an arguer uses to support a position.