This article aims at discussing two main definitions of the concept of interaction: the first
one assumes that an interaction is the sum of individual actions (inter-actions) while the
second one assumes that interaction is an inseparable unit of analysis. They constitute
what can be called a factorial vs. dialogical conception of interaction. After having
presented these two conceptions and shown some gaps between theoretical assumptions
and methodological practices, we discuss what methodological consequences for research
a dialogical conception of interaction may have, provide the example of a study which tried
to take these consequences into account, and conclude with some challenges that have to
be faced in future research.