Recent research suggests that peer-to-peer argumentation supports conceptual change in students knowledge structures in science and mathematics, provided that students actually juxtapose and evaluate different ideas in a critical, yet co-constructive manner. However, it is well known that this type of peer-to-peer dialogue is not easily elicited and sustained, especially on scientific topics. In this paper, we report on findings from research that investigates how the pursuing of different goals may result in more or less productive types of peer interaction and peer argumentation, and how this, in turn affects conceptual learning from these interactions. In study 1, we focused on the relation between students individual achievement goal orientations and four different types of peer interaction behavior, with the help of self-report questionnaires. In study 2, the effect of different interaction goal instructions (co-constructive vs. competitive) is tested on peer dialogue and on subsequent individual learning gains.