In this paper we attempt to identify which peer collaboration characteristics may be accountable for conceptual change through interaction. We focus on different socio-cognitive aspects of the peer dialogue and relate these with learning gains on the dyadic, as well as the individual level. The scientific topic that was used for this study concerns natural selection, a topic for which students' intuitive conceptions have been shown to be particularly robust. Learning tasks were designed according to the socio-cognitive conflict instructional paradigm. After receiving a short instructional intervention on natural selection, paired students were asked to collaboratively construct explanations for certain evolutionary phenomena while engaging in dialectical argumentation. Two quantitative coding schemes were developed, each with a different granularity: The first assessed discrete dialogue moves that pertained to dialectical argumentation and to consensual explanation development. The second scheme characterized the dialogue as a whole on a number of socio-cognitive dimensions. Results from analyses on the dyadic as well as the individual level revealed that the engagement in dialectical argumentation predicted conceptual learning gains, whereas consensual explanation development did not. These findings open up new venues for research on the mechanisms of learning in and from peer collaboration.